diff --git a/Makefile b/Makefile
index bca82f2bb62..af16c6094da 100644
--- a/Makefile
+++ b/Makefile
@@ -379,6 +379,8 @@ ifneq (,$(filter $(OSTYPE), osx freebsd))
 endif
 
 # target specific build options
+libponyrt.buildoptions = -DPONY_NO_ASSERT
+
 libponyc.buildoptions = -D__STDC_CONSTANT_MACROS
 libponyc.buildoptions += -D__STDC_FORMAT_MACROS
 libponyc.buildoptions += -D__STDC_LIMIT_MACROS
@@ -398,6 +400,8 @@ libgbenchmark.buildoptions := -DHAVE_POSIX_REGEX
 
 ponyc.buildoptions = $(libponyc.buildoptions)
 
+ponyc.linkoptions += -rdynamic
+
 ifeq ($(OSTYPE), linux)
   libponyrt-pic.buildoptions += -fpic
 endif
diff --git a/src/common/pony/detail/atomics.h b/src/common/pony/detail/atomics.h
index cf05efcb848..912890e607c 100644
--- a/src/common/pony/detail/atomics.h
+++ b/src/common/pony/detail/atomics.h
@@ -28,6 +28,9 @@ using std::atomic_compare_exchange_strong_explicit;
 using std::atomic_fetch_add_explicit;
 using std::atomic_fetch_sub_explicit;
 using std::atomic_thread_fence;
+using std::atomic_flag_test_and_set_explicit;
+
+using std::atomic_flag;
 #  endif
 #elif defined(__GNUC__) && !defined(__clang__)
 #  include <features.h>
@@ -46,6 +49,8 @@ using std::atomic_thread_fence;
 #  elif __GNUC_PREREQ(4, 7)
 // Valid on x86 and ARM given our uses of atomics.
 #    define PONY_ATOMIC(T) T
+#    define atomic_flag bool
+#    define ATOMIC_FLAG_INIT false
 #    define PONY_ATOMIC_BUILTINS
 #  else
 #    error "Please use GCC >= 4.7"
@@ -59,6 +64,8 @@ using std::atomic_thread_fence;
 #  elif __clang_major__ >= 3 && __clang_minor__ >= 3
 // Valid on x86 and ARM given our uses of atomics.
 #    define PONY_ATOMIC(T) T
+#    define atomic_flag bool
+#    define ATOMIC_FLAG_INIT false
 #    define PONY_ATOMIC_BUILTINS
 #  else
 #    error "Please use Clang >= 3.3"
@@ -205,6 +212,9 @@ namespace ponyint_atomics
 #    define atomic_thread_fence(MO) \
       __atomic_thread_fence(MO)
 
+#    define atomic_flag_test_and_set_explicit(PTR, MO) \
+      __atomic_test_and_set(PTR, MO)
+
 #    undef PONY_ATOMIC_BUILTINS
 #  endif
 #endif
diff --git a/src/common/ponyassert.h b/src/common/ponyassert.h
new file mode 100644
index 00000000000..80a0d8ec2b4
--- /dev/null
+++ b/src/common/ponyassert.h
@@ -0,0 +1,21 @@
+#ifndef PLATFORM_PONYASSERT_H
+#define PLATFORM_PONYASSERT_H
+
+#include "platform.h"
+
+PONY_EXTERN_C_BEGIN
+
+#if defined(NDEBUG) && defined(PONY_NO_ASSERT)
+#  define pony_assert(expr) ((void)0)
+#else
+#  define pony_assert(expr) \
+    ((expr) ? (void)0 : \
+      ponyint_assert_fail(#expr, __FILE__, __LINE__, __func__))
+#endif
+
+void ponyint_assert_fail(const char* expr, const char* file, size_t line,
+  const char* func);
+
+PONY_EXTERN_C_END
+
+#endif
diff --git a/src/libponyc/ast/ast.c b/src/libponyc/ast/ast.c
index a239b27b76c..ffc6873ac18 100644
--- a/src/libponyc/ast/ast.c
+++ b/src/libponyc/ast/ast.c
@@ -8,11 +8,11 @@
 #include "../pkg/program.h"
 #include "../pkg/package.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <assert.h>
 
 
 /* Every AST node has a parent field, which points to the parent node when
@@ -294,7 +294,7 @@ static bool hasparent(ast_t* ast)
 // Set both the parent and scope for the given node
 static void set_scope_and_parent(ast_t* ast, ast_t* parent)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   ast->parent = parent;
   ast_clearflag(ast, AST_ORPHAN);
@@ -303,7 +303,7 @@ static void set_scope_and_parent(ast_t* ast, ast_t* parent)
 // Set the scope for the given node, but set it no have no parent
 static void set_scope_no_parent(ast_t* ast, ast_t* scope)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   ast->parent = scope;
   ast_setflag(ast, AST_ORPHAN);
@@ -320,7 +320,7 @@ static ast_t* duplicate(ast_t* parent, ast_t* ast)
   if(ast == NULL)
     return NULL;
 
-  assert(ast_id(ast) != TK_PROGRAM && ast_id(ast) != TK_PACKAGE &&
+  pony_assert(ast_id(ast) != TK_PROGRAM && ast_id(ast) != TK_PACKAGE &&
     ast_id(ast) != TK_MODULE);
 
   ast_t* n = ast_token(token_dup(ast->t));
@@ -378,7 +378,7 @@ ast_t* ast_token(token_t* t)
 
 ast_t* ast_from(ast_t* ast, token_id id)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   ast_t* new_ast = ast_token(token_dup_new_id(ast->t, id));
   set_scope_no_parent(new_ast, ast->parent);
   return new_ast;
@@ -400,7 +400,7 @@ ast_t* ast_from_string(ast_t* ast, const char* name)
 
 ast_t* ast_from_int(ast_t* ast, uint64_t value)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   token_t* t = token_dup(ast->t);
   token_set_id(t, TK_INT);
 
@@ -414,7 +414,7 @@ ast_t* ast_from_int(ast_t* ast, uint64_t value)
 
 ast_t* ast_from_float(ast_t* ast, double value)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   token_t* t = token_dup(ast->t);
   token_set_id(t, TK_FLOAT);
   token_set_float(t, value);
@@ -431,56 +431,56 @@ ast_t* ast_dup(ast_t* ast)
 
 void ast_scope(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   ast->symtab = symtab_new();
 }
 
 bool ast_has_scope(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return ast->symtab != NULL;
 }
 
 symtab_t* ast_get_symtab(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return ast->symtab;
 }
 
 ast_t* ast_setid(ast_t* ast, token_id id)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   token_set_id(ast->t, id);
   return ast;
 }
 
 void ast_setpos(ast_t* ast, source_t* source, size_t line, size_t pos)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   token_set_pos(ast->t, source, line, pos);
 }
 
 token_id ast_id(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_get_id(ast->t);
 }
 
 size_t ast_line(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_line_number(ast->t);
 }
 
 size_t ast_pos(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_line_position(ast->t);
 }
 
 source_t* ast_source(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_source(ast->t);
 }
 
@@ -494,7 +494,7 @@ void* ast_data(ast_t* ast)
 
 ast_t* ast_setdata(ast_t* ast, void* data)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   ast->data = data;
   return ast;
 }
@@ -536,7 +536,7 @@ void ast_clearmightsend(ast_t* ast)
 
 void ast_inheritflags(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   for(ast_t* child = ast->child; child != NULL; child = ast_sibling(child))
     ast_setflag(ast, child->flags & AST_INHERIT_FLAGS);
@@ -544,24 +544,24 @@ void ast_inheritflags(ast_t* ast)
 
 int ast_checkflag(ast_t* ast, uint32_t flag)
 {
-  assert(ast != NULL);
-  assert((flag & AST_ALL_FLAGS) == flag);
+  pony_assert(ast != NULL);
+  pony_assert((flag & AST_ALL_FLAGS) == flag);
 
   return ast->flags & flag;
 }
 
 void ast_setflag(ast_t* ast, uint32_t flag)
 {
-  assert(ast != NULL);
-  assert((flag & AST_ALL_FLAGS) == flag);
+  pony_assert(ast != NULL);
+  pony_assert((flag & AST_ALL_FLAGS) == flag);
 
   ast->flags |= flag;
 }
 
 void ast_clearflag(ast_t* ast, uint32_t flag)
 {
-  assert(ast != NULL);
-  assert((flag & AST_ALL_FLAGS) == flag);
+  pony_assert(ast != NULL);
+  pony_assert((flag & AST_ALL_FLAGS) == flag);
 
   ast->flags &= ~flag;
 }
@@ -580,21 +580,21 @@ void ast_resetpass(ast_t* ast)
 
 const char* ast_get_print(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_print(ast->t);
 }
 
 const char* ast_name(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_string(ast->t);
 }
 
 
 const char* ast_nice_name(ast_t* ast)
 {
-  assert(ast != NULL);
-  assert(ast_id(ast) == TK_ID);
+  pony_assert(ast != NULL);
+  pony_assert(ast_id(ast) == TK_ID);
 
   if(ast->data != NULL)
     return (const char*)ast->data;
@@ -605,37 +605,37 @@ const char* ast_nice_name(ast_t* ast)
 
 size_t ast_name_len(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_string_len(ast->t);
 }
 
 void ast_set_name(ast_t* ast, const char* name)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   token_set_string(ast->t, name, 0);
 }
 
 double ast_float(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_float(ast->t);
 }
 
 lexint_t* ast_int(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return token_int(ast->t);
 }
 
 ast_t* ast_type(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return ast->type;
 }
 
 void ast_settype(ast_t* ast, ast_t* type)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   if(ast->type == type)
     return;
@@ -655,27 +655,27 @@ void ast_settype(ast_t* ast, ast_t* type)
 
 ast_t* ast_annotation(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return ast->annotation;
 }
 
 void ast_setannotation(ast_t* ast, ast_t* annotation)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   if(ast->annotation == annotation)
     return;
 
   ast_free(ast->annotation);
 
-  assert((annotation == NULL) || !hasparent(annotation));
+  pony_assert((annotation == NULL) || !hasparent(annotation));
 
   ast->annotation = annotation;
 }
 
 ast_t* ast_consumeannotation(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   ast_t* annotation = ast->annotation;
   ast->annotation = NULL;
@@ -685,7 +685,7 @@ ast_t* ast_consumeannotation(ast_t* ast)
 
 bool ast_has_annotation(ast_t* ast, const char* name)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   ast_t* annotation = ast->annotation;
 
@@ -706,7 +706,7 @@ bool ast_has_annotation(ast_t* ast, const char* name)
 
 void ast_erase(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   ast_t* child = ast->child;
 
@@ -764,13 +764,13 @@ ast_t* ast_parent(ast_t* ast)
 
 ast_t* ast_child(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   return ast->child;
 }
 
 ast_t* ast_childidx(ast_t* ast, size_t idx)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   ast_t* child = ast->child;
 
   while((child != NULL) && (idx > 0))
@@ -817,8 +817,8 @@ ast_t* ast_sibling(ast_t* ast)
 
 ast_t* ast_previous(ast_t* ast)
 {
-  assert(ast != NULL);
-  assert(hasparent(ast));
+  pony_assert(ast != NULL);
+  pony_assert(hasparent(ast));
 
   ast_t* last = NULL;
   ast_t* cur = ast->parent->child;
@@ -834,8 +834,8 @@ ast_t* ast_previous(ast_t* ast)
 
 size_t ast_index(ast_t* ast)
 {
-  assert(ast != NULL);
-  assert(hasparent(ast));
+  pony_assert(ast != NULL);
+  pony_assert(hasparent(ast));
 
   ast_t* child = ast->parent->child;
   size_t idx = 0;
@@ -950,7 +950,7 @@ void ast_inheritbranch(ast_t* dst, ast_t* src)
 
 void ast_consolidate_branches(ast_t* ast, size_t count)
 {
-  assert(hasparent(ast));
+  pony_assert(hasparent(ast));
 
   size_t i = HASHMAP_BEGIN;
   symbol_t* sym;
@@ -962,7 +962,7 @@ void ast_consolidate_branches(ast_t* ast, size_t count)
 
     if(sym->status == SYM_UNDEFINED)
     {
-      assert(sym->branch_count <= count);
+      pony_assert(sym->branch_count <= count);
 
       if((status == SYM_DEFINED) || (sym->branch_count == count))
       {
@@ -1086,9 +1086,9 @@ void ast_clear_local(ast_t* ast)
 
 ast_t* ast_add(ast_t* parent, ast_t* child)
 {
-  assert(parent != NULL);
-  assert(parent != child);
-  assert(parent->child != child);
+  pony_assert(parent != NULL);
+  pony_assert(parent != child);
+  pony_assert(parent->child != child);
 
   if(hasparent(child))
     child = ast_dup(child);
@@ -1101,15 +1101,15 @@ ast_t* ast_add(ast_t* parent, ast_t* child)
 
 ast_t* ast_add_sibling(ast_t* older_sibling, ast_t* new_sibling)
 {
-  assert(older_sibling != NULL);
-  assert(new_sibling != NULL);
-  assert(older_sibling != new_sibling);
-  assert(hasparent(older_sibling));
+  pony_assert(older_sibling != NULL);
+  pony_assert(new_sibling != NULL);
+  pony_assert(older_sibling != new_sibling);
+  pony_assert(hasparent(older_sibling));
 
   if(hasparent(new_sibling))
     new_sibling = ast_dup(new_sibling);
 
-  assert(new_sibling->sibling == NULL);
+  pony_assert(new_sibling->sibling == NULL);
 
   set_scope_and_parent(new_sibling, older_sibling->parent);
   new_sibling->sibling = older_sibling->sibling;
@@ -1133,9 +1133,9 @@ ast_t* ast_pop(ast_t* parent)
 
 ast_t* ast_append(ast_t* parent, ast_t* child)
 {
-  assert(parent != NULL);
-  assert(child != NULL);
-  assert(parent != child);
+  pony_assert(parent != NULL);
+  pony_assert(child != NULL);
+  pony_assert(parent != child);
 
   if(hasparent(child))
     child = ast_dup(child);
@@ -1159,21 +1159,21 @@ ast_t* ast_append(ast_t* parent, ast_t* child)
 
 ast_t* ast_list_append(ast_t* parent, ast_t** last_pointer, ast_t* new_child)
 {
-  assert(parent != NULL);
-  assert(last_pointer != NULL);
-  assert(new_child != NULL);
+  pony_assert(parent != NULL);
+  pony_assert(last_pointer != NULL);
+  pony_assert(new_child != NULL);
 
   if(*last_pointer == NULL)
   {
     // This is the first child for the parent
-    assert(parent->child == NULL);
+    pony_assert(parent->child == NULL);
     *last_pointer = ast_add(parent, new_child);
   }
   else
   {
     // This is not the first child, append to list
-    assert(parent->child != NULL);
-    assert((*last_pointer)->sibling == NULL);
+    pony_assert(parent->child != NULL);
+    pony_assert((*last_pointer)->sibling == NULL);
     *last_pointer = ast_add_sibling(*last_pointer, new_child);
   }
 
@@ -1182,8 +1182,8 @@ ast_t* ast_list_append(ast_t* parent, ast_t** last_pointer, ast_t* new_child)
 
 void ast_remove(ast_t* ast)
 {
-  assert(ast != NULL);
-  assert(hasparent(ast));
+  pony_assert(ast != NULL);
+  pony_assert(hasparent(ast));
 
   ast_t* last = ast_previous(ast);
 
@@ -1199,11 +1199,11 @@ void ast_remove(ast_t* ast)
 
 void ast_swap(ast_t* prev, ast_t* next)
 {
-  assert(prev != NULL);
-  assert(prev != next);
+  pony_assert(prev != NULL);
+  pony_assert(prev != next);
 
   ast_t* parent = ast_parent(prev);
-  assert(parent != NULL);
+  pony_assert(parent != NULL);
 
   if(hasparent(next))
     next = ast_dup(next);
@@ -1246,9 +1246,9 @@ void ast_replace(ast_t** prev, ast_t* next)
 void ast_reorder_children(ast_t* ast, const size_t* new_order,
   ast_t** shuffle_space)
 {
-  assert(ast != NULL);
-  assert(new_order != NULL);
-  assert(shuffle_space != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(new_order != NULL);
+  pony_assert(shuffle_space != NULL);
 
   size_t count = ast_childcount(ast);
 
@@ -1258,9 +1258,9 @@ void ast_reorder_children(ast_t* ast, const size_t* new_order,
   for(size_t i = 0; i < count; i++)
   {
     size_t index = new_order[i];
-    assert(index < count);
+    pony_assert(index < count);
     ast_t* t = shuffle_space[index];
-    assert(t != NULL);
+    pony_assert(t != NULL);
     ast_append(ast, t);
     shuffle_space[index] = NULL;
   }
@@ -1498,9 +1498,9 @@ void ast_error_continue(errors_t* errors, ast_t* ast, const char* fmt, ...)
 
 void ast_error_frame(errorframe_t* frame, ast_t* ast, const char* fmt, ...)
 {
-  assert(frame != NULL);
-  assert(ast != NULL);
-  assert(fmt != NULL);
+  pony_assert(frame != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(fmt != NULL);
 
   va_list ap;
   va_start(ap, fmt);
@@ -1512,15 +1512,15 @@ void ast_error_frame(errorframe_t* frame, ast_t* ast, const char* fmt, ...)
 void ast_get_children(ast_t* parent, size_t child_count,
   ast_t*** out_children)
 {
-  assert(parent != NULL);
-  assert(child_count > 0);
-  assert(out_children != NULL);
+  pony_assert(parent != NULL);
+  pony_assert(child_count > 0);
+  pony_assert(out_children != NULL);
 
   ast_t* p = parent->child;
 
   for(size_t i = 0; i < child_count; i++)
   {
-    assert(p != NULL);
+    pony_assert(p != NULL);
 
     if(out_children[i] != NULL)
       *(out_children[i]) = p;
@@ -1532,16 +1532,16 @@ void ast_get_children(ast_t* parent, size_t child_count,
 void ast_extract_children(ast_t* parent, size_t child_count,
   ast_t*** out_children)
 {
-  assert(parent != NULL);
-  assert(child_count > 0);
-  assert(out_children != NULL);
+  pony_assert(parent != NULL);
+  pony_assert(child_count > 0);
+  pony_assert(out_children != NULL);
 
   ast_t* p = parent->child;
   ast_t* last_remaining_sibling = NULL;
 
   for(size_t i = 0; i < child_count; i++)
   {
-    assert(p != NULL);
+    pony_assert(p != NULL);
     ast_t* next = p->sibling;
 
     if(out_children[i] != NULL)
diff --git a/src/libponyc/ast/bnfprint.c b/src/libponyc/ast/bnfprint.c
index 855520fae03..e14e4f8b70d 100644
--- a/src/libponyc/ast/bnfprint.c
+++ b/src/libponyc/ast/bnfprint.c
@@ -4,8 +4,8 @@
 #include "ast.h"
 #include "token.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdio.h>
-#include <assert.h>
 #include <string.h>
 
 /** This file contains the BNF printer, which prints out the Pony BNF in human
@@ -241,8 +241,8 @@ static bnf_t* bnf_copy(bnf_t* bnf, bnf_t** out_last_sibling)
 // New children go at the end of the child list.
 static bnf_t* bnf_add(bnf_t* bnf, bnf_t* parent)
 {
-  assert(bnf != NULL);
-  assert(parent != NULL);
+  pony_assert(bnf != NULL);
+  pony_assert(parent != NULL);
 
   if(parent->last_child == NULL)  // First node in list
     parent->child = bnf;
@@ -344,7 +344,7 @@ static void bnf_print(bnf_t* bnf, bool top_format)
       break;
 
     default:
-      assert(false);
+      pony_assert(false);
       break;
   }
 }
@@ -356,11 +356,11 @@ static void bnf_print(bnf_t* bnf, bool top_format)
 static void bnf_print_children(bnf_t* bnf, const char* separator,
   bool top_format, bool children_top_format)
 {
-  assert(bnf != NULL);
-  assert(separator != NULL);
+  pony_assert(bnf != NULL);
+  pony_assert(separator != NULL);
 
   bnf_t* child = bnf->child;
-  assert(child != NULL);
+  pony_assert(child != NULL);
 
   bool parens = !top_format && (child->sibling != NULL);
 
@@ -383,12 +383,12 @@ static void bnf_print_children(bnf_t* bnf, const char* separator,
 // Build a list of token references with the given node
 static void bnf_token_set(bnf_t* bnf, token_id* tokens, bool clean)
 {
-  assert(bnf != NULL);
+  pony_assert(bnf != NULL);
 
   for(int i = 0; tokens[i] != TK_NONE; i++)
   {
     bnf_t* p = bnf_add(bnf_create(BNF_TOKEN), bnf);
-    assert(p != NULL);
+    pony_assert(p != NULL);
 
     //token_id next = tokens[i + 1];
 
@@ -410,7 +410,7 @@ static void bnf_token_set(bnf_t* bnf, token_id* tokens, bool clean)
         p->name = lexer_print(tokens[i]);
         p->id = BNF_QUOTED_TOKEN;
 
-        assert(p->name != NULL);
+        pony_assert(p->name != NULL);
 
         if((clean && p->name[0] == '$') || tokens[i] == TK_NEWLINE)
         {
@@ -427,12 +427,12 @@ static void bnf_token_set(bnf_t* bnf, token_id* tokens, bool clean)
 // Build a list of rule references with the given node
 static void bnf_rule_set(bnf_t* bnf, const char** rules)
 {
-  assert(bnf != NULL);
+  pony_assert(bnf != NULL);
 
   for(int i = 0; rules[i] != NULL; i++)
   {
     bnf_t* p = bnf_add(bnf_create(BNF_RULE), bnf);
-    assert(p != NULL);
+    pony_assert(p != NULL);
     p->name = rules[i];
   }
 }
@@ -443,8 +443,8 @@ static void bnf_rule_set(bnf_t* bnf, const char** rules)
 // it and then free the child.
 static void bnf_use_child(bnf_t* bnf)
 {
-  assert(bnf != NULL);
-  assert(bnf->child != NULL);
+  pony_assert(bnf != NULL);
+  pony_assert(bnf->child != NULL);
 
   bnf_t* child = bnf->child;
 
@@ -462,8 +462,8 @@ static void bnf_use_child(bnf_t* bnf)
 // Find the rule with the specified name
 static bnf_t* bnf_find_def(bnf_t* tree, const char* name)
 {
-  assert(tree != NULL);
-  assert(name != NULL);
+  pony_assert(tree != NULL);
+  pony_assert(name != NULL);
 
   for(bnf_t* p = tree->child; p != NULL; p = p->sibling)
   {
@@ -472,7 +472,7 @@ static bnf_t* bnf_find_def(bnf_t* tree, const char* name)
   }
 
   // Not found, this is impossible if the parser compiles
-  assert(false);
+  pony_assert(false);
   return NULL;
 }
 
@@ -483,8 +483,8 @@ static bnf_t* bnf_find_def(bnf_t* tree, const char* name)
 // The out_changed variable is set to true when any simplifications occur.
 static void bnf_simplify_node(bnf_t* tree, bnf_t* bnf, bool *out_changed)
 {
-  assert(bnf != NULL);
-  assert(out_changed != NULL);
+  pony_assert(bnf != NULL);
+  pony_assert(out_changed != NULL);
 
   switch(bnf->id)
   {
@@ -568,10 +568,10 @@ static void bnf_simplify_node(bnf_t* tree, bnf_t* bnf, bool *out_changed)
         break;
 
       bnf_t* def = bnf_find_def(tree, bnf->name);
-      assert(def != NULL);
+      pony_assert(def != NULL);
 
       bnf_t* rule = def->child;
-      assert(rule != NULL);
+      pony_assert(rule != NULL);
 
       // We inline rules that are nevers, nops, single token / rule references
       // or have been explicitly marked to inline
@@ -588,7 +588,7 @@ static void bnf_simplify_node(bnf_t* tree, bnf_t* bnf, bool *out_changed)
 
         // Child of def should only ever have one child, so don't need to worry
         // about copying siblings
-        assert(rule->sibling == NULL);
+        pony_assert(rule->sibling == NULL);
 
         // Don't worry about simplifying children now, leave that til the next
         // iteration
@@ -610,7 +610,7 @@ static void bnf_simplify_node(bnf_t* tree, bnf_t* bnf, bool *out_changed)
 static void bnf_simplify_children(bnf_t* tree, bnf_t* parent, bool* out_never,
   bool* out_nop, bool *out_changed)
 {
-  assert(parent != NULL);
+  pony_assert(parent != NULL);
 
   if(out_never != NULL) *out_never = false;
   if(out_nop != NULL) *out_nop = false;
@@ -658,7 +658,7 @@ static void bnf_simplify_children(bnf_t* tree, bnf_t* parent, bool* out_never,
 // Simplify the given tree as far as possible
 static void bnf_simplify(bnf_t* tree)
 {
-  assert(tree != NULL);
+  pony_assert(tree != NULL);
 
   bool changed = true;
 
@@ -673,7 +673,7 @@ static void bnf_simplify(bnf_t* tree)
 // Add extra rules to get round the ANTLR interpreter bug
 static void bnf_avoid_antlr_bug(bnf_t* tree, bnf_t* bnf)
 {
-  assert(tree != NULL);
+  pony_assert(tree != NULL);
 
   if(bnf == NULL)
     return;
@@ -688,12 +688,12 @@ static void bnf_avoid_antlr_bug(bnf_t* tree, bnf_t* bnf)
     return;
 
   bnf_t* or_node = bnf->child;
-  assert(or_node != NULL);
+  pony_assert(or_node != NULL);
 
   if(or_node->id != BNF_OR)
     return;
 
-  assert(or_node->child != NULL);
+  pony_assert(or_node->child != NULL);
 
   bnf_t* second_child = or_node->child->sibling;
 
@@ -704,7 +704,7 @@ static void bnf_avoid_antlr_bug(bnf_t* tree, bnf_t* bnf)
   // This is the bug case. Move 'or' node into its own rule.
   int rule_no = tree->hack_count++;
 
-  assert(tree->last_child != NULL);
+  pony_assert(tree->last_child != NULL);
   bnf_t* new_rule = bnf_create(BNF_DEF);
   new_rule->hack_count = rule_no;
   new_rule->child = or_node;
@@ -722,8 +722,8 @@ static void bnf_avoid_antlr_bug(bnf_t* tree, bnf_t* bnf)
 // Mark rule definitions that are referenced from within the given subtree
 static void bnf_mark_refd_defs(bnf_t* tree, bnf_t* bnf)
 {
-  assert(tree != NULL);
-  assert(bnf != NULL);
+  pony_assert(tree != NULL);
+  pony_assert(bnf != NULL);
 
   for(bnf_t* p = bnf; p != NULL; p = p->sibling)
   {
@@ -733,7 +733,7 @@ static void bnf_mark_refd_defs(bnf_t* tree, bnf_t* bnf)
     if(p->id == BNF_RULE && p->name != NULL)
     {
       bnf_t* rule = bnf_find_def(tree, p->name);
-      assert(rule != NULL);
+      pony_assert(rule != NULL);
       rule->used = true;
     }
   }
@@ -871,7 +871,7 @@ static bnf_t* bnf_def(bool clean)
 void print_grammar(bool antlr, bool clean)
 {
   bnf_t* tree = bnf_def(clean);
-  assert(tree != NULL);
+  pony_assert(tree != NULL);
 
   bnf_simplify(tree);
 
diff --git a/src/libponyc/ast/error.c b/src/libponyc/ast/error.c
index 746a5ffbb93..9db136318ac 100644
--- a/src/libponyc/ast/error.c
+++ b/src/libponyc/ast/error.c
@@ -1,10 +1,10 @@
 #include "error.h"
 #include "stringtab.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <assert.h>
 
 #define LINE_LEN 1024
 
@@ -146,7 +146,7 @@ static void errors_push(errors_t* errors, errormsg_t* e)
 
 static void append_to_frame(errorframe_t* frame, errormsg_t* e)
 {
-  assert(frame != NULL);
+  pony_assert(frame != NULL);
 
   if(*frame == NULL)
   {
@@ -262,14 +262,14 @@ void error_continue(errors_t* errors, source_t* source, size_t line, size_t pos,
 void errorframev(errorframe_t* frame, source_t* source, size_t line,
   size_t pos, const char* fmt, va_list ap)
 {
-  assert(frame != NULL);
+  pony_assert(frame != NULL);
   append_to_frame(frame, make_errorv(source, line, pos, fmt, ap));
 }
 
 void errorframe(errorframe_t* frame, source_t* source, size_t line, size_t pos,
   const char* fmt, ...)
 {
-  assert(frame != NULL);
+  pony_assert(frame != NULL);
 
   va_list ap;
   va_start(ap, fmt);
@@ -304,8 +304,8 @@ void errorf(errors_t* errors, const char* file, const char* fmt, ...)
 
 void errorframe_append(errorframe_t* first, errorframe_t* second)
 {
-  assert(first != NULL);
-  assert(second != NULL);
+  pony_assert(first != NULL);
+  pony_assert(second != NULL);
 
   append_to_frame(first, *second);
   *second = NULL;
@@ -313,13 +313,13 @@ void errorframe_append(errorframe_t* first, errorframe_t* second)
 
 bool errorframe_has_errors(errorframe_t* frame)
 {
-  assert(frame != NULL);
+  pony_assert(frame != NULL);
   return frame != NULL;
 }
 
 void errorframe_report(errorframe_t* frame, errors_t* errors)
 {
-  assert(frame != NULL);
+  pony_assert(frame != NULL);
 
   if(*frame != NULL)
     errors_push(errors, *frame);
@@ -329,7 +329,7 @@ void errorframe_report(errorframe_t* frame, errors_t* errors)
 
 void errorframe_discard(errorframe_t* frame)
 {
-  assert(frame != NULL);
+  pony_assert(frame != NULL);
 
   error_free(*frame);
   *frame = NULL;
diff --git a/src/libponyc/ast/frame.c b/src/libponyc/ast/frame.c
index a7aa80667c2..f46cfc2d25c 100644
--- a/src/libponyc/ast/frame.c
+++ b/src/libponyc/ast/frame.c
@@ -2,8 +2,8 @@
 #include "ast.h"
 #include "error.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 static bool push_frame(typecheck_t* t)
 {
@@ -273,7 +273,7 @@ bool frame_push(typecheck_t* t, ast_t* ast)
 void frame_pop(typecheck_t* t)
 {
   typecheck_frame_t* f = t->frame;
-  assert(f != NULL);
+  pony_assert(f != NULL);
 
   t->frame = f->prev;
   POOL_FREE(typecheck_frame_t, f);
diff --git a/src/libponyc/ast/id.c b/src/libponyc/ast/id.c
index a9fd3e435fa..3fda0243ce5 100644
--- a/src/libponyc/ast/id.c
+++ b/src/libponyc/ast/id.c
@@ -1,16 +1,16 @@
-#include <assert.h>
+#include "ponyassert.h"
 #include "id.h"
 #include "id_internal.h"
 
 
 bool check_id(pass_opt_t* opt, ast_t* id_node, const char* desc, int spec)
 {
-  assert(id_node != NULL);
-  assert(ast_id(id_node) == TK_ID);
-  assert(desc != NULL);
+  pony_assert(id_node != NULL);
+  pony_assert(ast_id(id_node) == TK_ID);
+  pony_assert(desc != NULL);
 
   const char* name = ast_name(id_node);
-  assert(name != NULL);
+  pony_assert(name != NULL);
   char prev = '\0';
 
   // Ignore leading $, handled by lexer
@@ -111,7 +111,7 @@ bool check_id(pass_opt_t* opt, ast_t* id_node, const char* desc, int spec)
     return true;
 
   // Should only be ticks left
-  assert(*name == '\'');
+  pony_assert(*name == '\'');
 
   if((spec & ALLOW_TICK) == 0)
   {
diff --git a/src/libponyc/ast/lexer.c b/src/libponyc/ast/lexer.c
index 3a21328f112..6fde5b1b7f4 100644
--- a/src/libponyc/ast/lexer.c
+++ b/src/libponyc/ast/lexer.c
@@ -4,11 +4,11 @@
 #include "token.h"
 #include "stringtab.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
 #include <math.h>
-#include <assert.h>
 
 
 struct lexer_t
@@ -384,7 +384,7 @@ static token_t* make_token_with_text(lexer_t* lexer, token_id id)
  */
 static void consume_chars(lexer_t* lexer, size_t count)
 {
-  assert(lexer->len >= count);
+  pony_assert(lexer->len >= count);
 
   if(count == 0)
     return;
@@ -754,7 +754,7 @@ static int escape(lexer_t* lexer, bool unicode_allowed, bool is_string)
 // Append the given value to the current token text, UTF-8 encoded
 static void append_utf8(lexer_t* lexer, int value)
 {
-  assert(value >= 0 && value <= 0x10FFFF);
+  pony_assert(value >= 0 && value <= 0x10FFFF);
 
   if(value <= 0x7F)
   {
@@ -955,7 +955,7 @@ static token_t* real(lexer_t* lexer, lexint_t* integral_value)
 
   uint32_t mantissa_digit_count = 0;
   char c = look(lexer);
-  assert(c == '.' || c == 'e' || c == 'E');
+  pony_assert(c == '.' || c == 'e' || c == 'E');
 
   if(c == '.')
   {
@@ -1208,7 +1208,7 @@ static token_t* symbol(lexer_t* lexer)
 
 lexer_t* lexer_open(source_t* source, errors_t* errors)
 {
-  assert(source != NULL);
+  pony_assert(source != NULL);
 
   lexer_t* lexer = POOL_ALLOC(lexer_t);
   memset(lexer, 0, sizeof(lexer_t));
@@ -1238,7 +1238,7 @@ void lexer_close(lexer_t* lexer)
 
 token_t* lexer_next(lexer_t* lexer)
 {
-  assert(lexer != NULL);
+  pony_assert(lexer != NULL);
 
   token_t* t = NULL;
 
@@ -1297,7 +1297,7 @@ token_t* lexer_next(lexer_t* lexer)
         else if(isalpha(c) || (c == '_'))
         {
           t = keyword(lexer, true);
-          assert(t != NULL);
+          pony_assert(t != NULL);
         }
         else
         {
diff --git a/src/libponyc/ast/parserapi.c b/src/libponyc/ast/parserapi.c
index 2ac623ef3f1..84a04d3dac5 100644
--- a/src/libponyc/ast/parserapi.c
+++ b/src/libponyc/ast/parserapi.c
@@ -1,7 +1,7 @@
 #include "parserapi.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdlib.h>
-#include <assert.h>
 #include <stdio.h>
 
 
@@ -68,9 +68,9 @@ static void consume_token_no_ast(parser_t* parser)
 static void syntax_error(parser_t* parser, const char* expected,
   ast_t* ast, const char* terminating)
 {
-  assert(parser != NULL);
-  assert(expected != NULL);
-  assert(parser->token != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(expected != NULL);
+  pony_assert(parser->token != NULL);
 
   if(parser->last_matched == NULL)
   {
@@ -87,7 +87,7 @@ static void syntax_error(parser_t* parser, const char* expected,
     }
     else
     {
-      assert(ast != NULL);
+      pony_assert(ast != NULL);
       ast_error(parser->errors, ast, "syntax error: unterminated %s",
         terminating);
       error_continue(parser->errors, parser->source,
@@ -103,8 +103,8 @@ static void syntax_error(parser_t* parser, const char* expected,
 
 static void default_builder(rule_state_t* state, ast_t* new_ast)
 {
-  assert(state != NULL);
-  assert(new_ast != NULL);
+  pony_assert(state != NULL);
+  pony_assert(new_ast != NULL);
 
   // Existing AST goes at the top
 
@@ -131,8 +131,8 @@ static void default_builder(rule_state_t* state, ast_t* new_ast)
 
 void infix_builder(rule_state_t* state, ast_t* new_ast)
 {
-  assert(state != NULL);
-  assert(new_ast != NULL);
+  pony_assert(state != NULL);
+  pony_assert(new_ast != NULL);
 
   // New AST goes at the top
   ast_add(new_ast, state->ast);
@@ -143,8 +143,8 @@ void infix_builder(rule_state_t* state, ast_t* new_ast)
 
 void infix_reverse_builder(rule_state_t* state, ast_t* new_ast)
 {
-  assert(state != NULL);
-  assert(new_ast != NULL);
+  pony_assert(state != NULL);
+  pony_assert(new_ast != NULL);
 
   // New AST goes at the top, existing goes on the right
   ast_append(new_ast, state->ast);
@@ -156,8 +156,8 @@ void infix_reverse_builder(rule_state_t* state, ast_t* new_ast)
 
 static void annotation_builder(rule_state_t* state, ast_t* new_ast)
 {
-  assert(state != NULL);
-  assert(new_ast != NULL);
+  pony_assert(state != NULL);
+  pony_assert(new_ast != NULL);
 
   ast_setannotation(state->ast, new_ast);
 }
@@ -168,8 +168,8 @@ static void annotation_builder(rule_state_t* state, ast_t* new_ast)
 // Process any deferred token we have
 static void process_deferred_ast(parser_t* parser, rule_state_t* state)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
 
   if(state->deferred)
   {
@@ -185,10 +185,10 @@ static void process_deferred_ast(parser_t* parser, rule_state_t* state)
 static void add_ast(parser_t* parser, rule_state_t* state, ast_t* new_ast,
   builder_fn_t build_fn)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
-  assert(new_ast != NULL && new_ast != PARSE_ERROR);
-  assert(build_fn != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
+  pony_assert(new_ast != NULL && new_ast != PARSE_ERROR);
+  pony_assert(build_fn != NULL);
 
   process_deferred_ast(parser, state);
 
@@ -209,7 +209,7 @@ static void add_ast(parser_t* parser, rule_state_t* state, ast_t* new_ast,
 // Add an AST node for the specified token, which may be deferred
 void add_deferrable_ast(parser_t* parser, rule_state_t* state, token_id id)
 {
-  assert(parser->token != NULL);
+  pony_assert(parser->token != NULL);
 
   if(!state->matched && state->ast == NULL && !state->deferred)
   {
@@ -229,9 +229,9 @@ void add_deferrable_ast(parser_t* parser, rule_state_t* state, token_id id)
 // The token set must be TK_NONE terminated
 static void ditch_restart(parser_t* parser, rule_state_t* state)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
-  assert(state->restart != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
+  pony_assert(state->restart != NULL);
 
   if(trace_enable)
     fprintf(stderr, "Rule %s: Attempting recovery:\n", state->fn_name);
@@ -265,8 +265,8 @@ static void ditch_restart(parser_t* parser, rule_state_t* state)
 // Propgate an error, handling AST tidy up and restart points
 static ast_t* propogate_error(parser_t* parser, rule_state_t* state)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
 
   ast_free(state->ast);
   state->ast = NULL;
@@ -297,8 +297,8 @@ static ast_t* propogate_error(parser_t* parser, rule_state_t* state)
 static ast_t* handle_found(parser_t* parser, rule_state_t* state,
   ast_t* new_ast, builder_fn_t build_fn, bool* out_found)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
 
   if(out_found != NULL)
     *out_found = true;
@@ -333,9 +333,9 @@ static ast_t* handle_found(parser_t* parser, rule_state_t* state,
 static ast_t* handle_not_found(parser_t* parser, rule_state_t* state,
   const char* desc, const char* terminating, bool* out_found)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
-  assert(desc != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
+  pony_assert(desc != NULL);
 
   if(out_found != NULL)
     *out_found = false;
@@ -401,9 +401,9 @@ ast_t* parse_token_set(parser_t* parser, rule_state_t* state, const char* desc,
   const char* terminating, const token_id* id_set, bool make_ast,
   bool* out_found)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
-  assert(id_set != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
+  pony_assert(id_set != NULL);
 
   token_id id = current_token_id(parser);
 
@@ -427,7 +427,7 @@ ast_t* parse_token_set(parser_t* parser, rule_state_t* state, const char* desc,
     // Match new line if the next token is the first on a line
     if(*p == TK_NEWLINE)
     {
-      assert(parser->token != NULL);
+      pony_assert(parser->token != NULL);
       size_t last_token_line = parser->last_token_line;
       size_t next_token_line = token_line_number(parser->token);
       bool is_newline = (next_token_line != last_token_line);
@@ -483,10 +483,10 @@ ast_t* parse_token_set(parser_t* parser, rule_state_t* state, const char* desc,
 ast_t* parse_rule_set(parser_t* parser, rule_state_t* state, const char* desc,
   const rule_t* rule_set, bool* out_found, bool annotate)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
-  assert(desc != NULL);
-  assert(rule_set != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
+  pony_assert(desc != NULL);
+  pony_assert(rule_set != NULL);
 
   token_id id = current_token_id(parser);
 
@@ -525,7 +525,7 @@ ast_t* parse_rule_set(parser_t* parser, rule_state_t* state, const char* desc,
 // Set the data flags to use for the next token consumed from the source
 void parse_set_next_flags(parser_t* parser, uint32_t flags)
 {
-  assert(parser != NULL);
+  pony_assert(parser != NULL);
   parser->next_flags = flags;
 }
 
@@ -541,8 +541,8 @@ void parse_set_next_flags(parser_t* parser, uint32_t flags)
  */
 ast_t* parse_rule_complete(parser_t* parser, rule_state_t* state)
 {
-  assert(parser != NULL);
-  assert(state != NULL);
+  pony_assert(parser != NULL);
+  pony_assert(state != NULL);
 
   process_deferred_ast(parser, state);
 
@@ -578,7 +578,7 @@ ast_t* parse_rule_complete(parser_t* parser, rule_state_t* state)
   if(trace_enable)
     fprintf(stderr, "Rule %s: Restart check error\n", state->fn_name);
 
-  assert(parser->token != NULL);
+  pony_assert(parser->token != NULL);
   error(parser->errors, parser->source, token_line_number(parser->token),
     token_line_position(parser->token),
     "syntax error: unexpected token %s after %s", token_print(parser->token),
@@ -602,9 +602,9 @@ void parse_trace(bool enable)
 bool parse(ast_t* package, source_t* source, rule_t start, const char* expected,
   errors_t* errors)
 {
-  assert(package != NULL);
-  assert(source != NULL);
-  assert(expected != NULL);
+  pony_assert(package != NULL);
+  pony_assert(source != NULL);
+  pony_assert(expected != NULL);
 
   // Open the lexer
   lexer_t* lexer = lexer_open(source, errors);
@@ -658,8 +658,8 @@ bool parse(ast_t* package, source_t* source, rule_t start, const char* expected,
     return false;
   }
 
-  assert(ast_id(ast) == TK_MODULE);
-  assert(ast_data(ast) == NULL);
+  pony_assert(ast_id(ast) == TK_MODULE);
+  pony_assert(ast_data(ast) == NULL);
   ast_setdata(ast, source);
   ast_add(package, ast);
   return true;
diff --git a/src/libponyc/ast/parserapi.h b/src/libponyc/ast/parserapi.h
index bc258d559d0..1b2744c014d 100644
--- a/src/libponyc/ast/parserapi.h
+++ b/src/libponyc/ast/parserapi.h
@@ -6,10 +6,10 @@
 #include "lexer.h"
 #include "ast.h"
 #include "token.h"
+#include "ponyassert.h"
 #include <stdbool.h>
 #include <limits.h>
 #include <stdio.h>
-#include <assert.h>
 
 PONY_EXTERN_C_BEGIN
 
@@ -449,7 +449,7 @@ bool parse(ast_t* package, source_t* source, rule_t start, const char* expected,
 #define REORDER(...) \
   { \
     static const size_t order[] = { __VA_ARGS__ }; \
-    assert(ast_childcount(state.ast) == (sizeof(order) / sizeof(size_t))); \
+    pony_assert(ast_childcount(state.ast) == (sizeof(order) / sizeof(size_t))); \
     static ast_t* shuffle[sizeof(order) / sizeof(size_t)]; \
     ast_reorder_children(state.ast, order, shuffle); \
     state.last_child = NULL; \
diff --git a/src/libponyc/ast/printbuf.c b/src/libponyc/ast/printbuf.c
index c31e0778396..54e7acb54fd 100644
--- a/src/libponyc/ast/printbuf.c
+++ b/src/libponyc/ast/printbuf.c
@@ -1,8 +1,8 @@
 #include "printbuf.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
 #include <stdio.h>
-#include <assert.h>
 
 printbuf_t* printbuf_new()
 {
@@ -53,7 +53,7 @@ void printbuf(printbuf_t* buf, const char* fmt, ...)
     r = vsnprintf(buf->m + buf->offset, avail, fmt, ap);
     va_end(ap);
 
-    assert((r > 0) && ((size_t)r < buf->size));
+    pony_assert((r > 0) && ((size_t)r < buf->size));
   }
 
   buf->offset += r;
diff --git a/src/libponyc/ast/symtab.c b/src/libponyc/ast/symtab.c
index 8003588201e..9a311102495 100644
--- a/src/libponyc/ast/symtab.c
+++ b/src/libponyc/ast/symtab.c
@@ -3,11 +3,11 @@
 #include "ast.h"
 #include "id.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <ctype.h>
-#include <assert.h>
 
 static size_t sym_hash(symbol_t* sym)
 {
diff --git a/src/libponyc/ast/token.c b/src/libponyc/ast/token.c
index b02b29f8974..e85b49090f4 100644
--- a/src/libponyc/ast/token.c
+++ b/src/libponyc/ast/token.c
@@ -2,10 +2,10 @@
 #include "lexer.h"
 #include "stringtab.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <assert.h>
 
 typedef struct token_t
 {
@@ -39,7 +39,7 @@ token_t* token_new(token_id id)
 
 token_t* token_dup(token_t* token)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
   token_t* t = POOL_ALLOC(token_t);
   memcpy(t, token, sizeof(token_t));
   t->printed = NULL;
@@ -71,46 +71,46 @@ void token_free(token_t* token)
 
 token_id token_get_id(token_t* token)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
   return token->id;
 }
 
 
 const char* token_string(token_t* token)
 {
-  assert(token != NULL);
-  assert(token->id == TK_STRING || token->id == TK_ID);
+  pony_assert(token != NULL);
+  pony_assert(token->id == TK_STRING || token->id == TK_ID);
   return token->string;
 }
 
 
 size_t token_string_len(token_t* token)
 {
-  assert(token != NULL);
-  assert(token->id == TK_STRING || token->id == TK_ID);
+  pony_assert(token != NULL);
+  pony_assert(token->id == TK_STRING || token->id == TK_ID);
   return token->str_length;
 }
 
 
 double token_float(token_t* token)
 {
-  assert(token != NULL);
-  assert(token->id == TK_FLOAT);
+  pony_assert(token != NULL);
+  pony_assert(token->id == TK_FLOAT);
   return token->real;
 }
 
 
 lexint_t* token_int(token_t* token)
 {
-  assert(token != NULL);
-  assert(token->id == TK_INT);
+  pony_assert(token != NULL);
+  pony_assert(token->id == TK_INT);
   return &token->integer;
 }
 
 
 const char* token_print(token_t* token)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
 
   switch(token->id)
   {
@@ -163,7 +163,7 @@ const char* token_print(token_t* token)
 
 char* token_print_escaped(token_t* token)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
   const char* str = NULL;
   size_t str_len = 0;
 
@@ -244,21 +244,21 @@ const char* token_id_desc(token_id id)
 
 source_t* token_source(token_t* token)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
   return token->source;
 }
 
 
 size_t token_line_number(token_t* token)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
   return token->line;
 }
 
 
 size_t token_line_position(token_t* token)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
   return token->pos;
 }
 
@@ -267,16 +267,16 @@ size_t token_line_position(token_t* token)
 
 void token_set_id(token_t* token, token_id id)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
   token->id = id;
 }
 
 
 void token_set_string(token_t* token, const char* value, size_t length)
 {
-  assert(token != NULL);
-  assert(token->id == TK_STRING || token->id == TK_ID);
-  assert(value != NULL);
+  pony_assert(token != NULL);
+  pony_assert(token->id == TK_STRING || token->id == TK_ID);
+  pony_assert(value != NULL);
 
   if(length == 0)
     length = strlen(value);
@@ -288,23 +288,23 @@ void token_set_string(token_t* token, const char* value, size_t length)
 
 void token_set_float(token_t* token, double value)
 {
-  assert(token != NULL);
-  assert(token->id == TK_FLOAT);
+  pony_assert(token != NULL);
+  pony_assert(token->id == TK_FLOAT);
   token->real = value;
 }
 
 
 void token_set_int(token_t* token, lexint_t* value)
 {
-  assert(token != NULL);
-  assert(token->id == TK_INT);
+  pony_assert(token != NULL);
+  pony_assert(token->id == TK_INT);
   token->integer = *value;
 }
 
 
 void token_set_pos(token_t* token, source_t* source, size_t line, size_t pos)
 {
-  assert(token != NULL);
+  pony_assert(token != NULL);
 
   if(source != NULL)
     token->source = source;
diff --git a/src/libponyc/ast/treecheck.c b/src/libponyc/ast/treecheck.c
index 698ec11582b..13dc7a98712 100644
--- a/src/libponyc/ast/treecheck.c
+++ b/src/libponyc/ast/treecheck.c
@@ -1,8 +1,8 @@
 #include "treecheck.h"
 #include "ast.h"
+#include "ponyassert.h"
 #include <stdbool.h>
 #include <stdio.h>
-#include <assert.h>
 
 
 // This define causes the tree checker to assert immediately on error, rather
@@ -36,7 +36,7 @@ typedef struct check_state_t
 // Print an error preamble for the given node.
 static void error_preamble(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   fprintf(stderr, "Internal error: AST node %d (%s), ", ast_id(ast),
     ast_get_print(ast));
@@ -47,7 +47,7 @@ static void error_preamble(ast_t* ast)
 // The id list must be TK_EOF terminated.
 static bool is_id_in_list(token_id id, const token_id* list)
 {
-  assert(list != NULL);
+  pony_assert(list != NULL);
 
   for(size_t i = 0; list[i] != TK_EOF; i++)
     if(list[i] == id)
@@ -62,8 +62,8 @@ static bool is_id_in_list(token_id id, const token_id* list)
 static check_res_t check_from_list(ast_t* ast, const check_fn_t *rules,
   errors_t* errors)
 {
-  assert(ast != NULL);
-  assert(rules != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(rules != NULL);
 
   // Check rules in given list
   for(const check_fn_t* p = rules; *p != NULL; p++)
@@ -84,9 +84,9 @@ static check_res_t check_from_list(ast_t* ast, const check_fn_t *rules,
 static bool check_children(ast_t* ast, check_state_t* state,
   const check_fn_t *rules, size_t min_count, size_t max_count, errors_t* errors)
 {
-  assert(ast != NULL);
-  assert(state != NULL);
-  assert(min_count <= max_count);
+  pony_assert(ast != NULL);
+  pony_assert(state != NULL);
+  pony_assert(min_count <= max_count);
 
   size_t found_count = 0;
 
@@ -120,7 +120,7 @@ static bool check_children(ast_t* ast, check_state_t* state,
     ast_error(state->errors, ast, "Here");
     ast_fprint(stderr, ast);
 #ifdef IMMEDIATE_FAIL
-    assert(false);
+    pony_assert(false);
 #endif
   }
   else
@@ -131,7 +131,7 @@ static bool check_children(ast_t* ast, check_state_t* state,
     ast_error(state->errors, ast, "Here");
     ast_fprint(stderr, ast);
 #ifdef IMMEDIATE_FAIL
-    assert(false);
+    pony_assert(false);
 #endif
   }
 
@@ -146,8 +146,8 @@ static bool check_children(ast_t* ast, check_state_t* state,
 static check_res_t check_extras(ast_t* ast, check_state_t* state,
   errors_t* errors)
 {
-  assert(ast != NULL);
-  assert(state != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(state != NULL);
 
 
   ast_t* type_field = ast_type(ast);
@@ -161,7 +161,7 @@ static check_res_t check_extras(ast_t* ast, check_state_t* state,
       ast_error(state->errors, ast, "Here");
       ast_fprint(stderr, ast);
 #ifdef IMMEDIATE_FAIL
-      assert(false);
+      pony_assert(false);
 #endif
       return CHK_ERROR;
     }
@@ -178,7 +178,7 @@ static check_res_t check_extras(ast_t* ast, check_state_t* state,
       ast_error(state->errors, ast, "Here");
       ast_fprint(stderr, ast);
 #ifdef IMMEDIATE_FAIL
-      assert(false);
+      pony_assert(false);
 #endif
       return CHK_ERROR;
     }
@@ -192,7 +192,7 @@ static check_res_t check_extras(ast_t* ast, check_state_t* state,
     ast_error(state->errors, ast, "Here");
     ast_fprint(stderr, ast);
 #ifdef IMMEDIATE_FAIL
-    assert(false);
+    pony_assert(false);
 #endif
     return CHK_ERROR;
   }
@@ -204,7 +204,7 @@ static check_res_t check_extras(ast_t* ast, check_state_t* state,
     ast_error(state->errors, ast, "Here");
     ast_fprint(stderr, ast);
 #ifdef IMMEDIATE_FAIL
-    assert(false);
+    pony_assert(false);
 #endif
     return CHK_ERROR;
   }
@@ -216,7 +216,7 @@ static check_res_t check_extras(ast_t* ast, check_state_t* state,
     ast_error(state->errors, ast, "Here");
     ast_fprint(stderr, ast);
 #ifdef IMMEDIATE_FAIL
-    assert(false);
+    pony_assert(false);
 #endif
     return CHK_ERROR;
   }
@@ -228,7 +228,7 @@ static check_res_t check_extras(ast_t* ast, check_state_t* state,
     ast_error(state->errors, ast, "Here");
     ast_fprint(stderr, ast);
 #ifdef IMMEDIATE_FAIL
-    assert(false);
+    pony_assert(false);
 #endif
     return CHK_ERROR;
   }
@@ -307,9 +307,9 @@ void check_tree(ast_t* tree, errors_t* errors)
   (void)errors;
 #else
   // Only check tree in debug builds.
-  assert(tree != NULL);
+  pony_assert(tree != NULL);
   check_res_t r = check_root(tree, errors);
-  assert(r != CHK_ERROR);
+  pony_assert(r != CHK_ERROR);
 
   // Ignore CHK_NOT_FOUND, that means we weren't given a whole tree.
 #endif
diff --git a/src/libponyc/codegen/codegen.c b/src/libponyc/codegen/codegen.c
index 289e7961dc8..e347fd7e2c9 100644
--- a/src/libponyc/codegen/codegen.c
+++ b/src/libponyc/codegen/codegen.c
@@ -13,13 +13,13 @@
 #include "../type/lookup.h"
 #include "../../libponyrt/mem/heap.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 
 #include <platform.h>
 #include <llvm-c/Initialization.h>
 #include <llvm-c/ExecutionEngine.h>
 #include <llvm-c/Linker.h>
 #include <string.h>
-#include <assert.h>
 
 struct compile_local_t
 {
diff --git a/src/libponyc/codegen/genbox.c b/src/libponyc/codegen/genbox.c
index c88d7b88ab7..61b09cf7f1d 100644
--- a/src/libponyc/codegen/genbox.c
+++ b/src/libponyc/codegen/genbox.c
@@ -2,7 +2,7 @@
 #include "gencall.h"
 #include "genname.h"
 #include "gentype.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 LLVMValueRef gen_box(compile_t* c, ast_t* type, LLVMValueRef value)
 {
@@ -12,7 +12,7 @@ LLVMValueRef gen_box(compile_t* c, ast_t* type, LLVMValueRef value)
     return value;
 
   reach_type_t* t = reach_type(c->reach, type);
-  assert(t != NULL);
+  pony_assert(t != NULL);
 
   if(l_type != t->primitive)
     return NULL;
@@ -40,7 +40,7 @@ LLVMValueRef gen_unbox(compile_t* c, ast_t* type, LLVMValueRef object)
     return object;
 
   reach_type_t* t = reach_type(c->reach, type);
-  assert(t != NULL);
+  pony_assert(t != NULL);
 
   if(t->primitive == NULL)
     return object;
diff --git a/src/libponyc/codegen/gencall.c b/src/libponyc/codegen/gencall.c
index 25c4aeb57d0..f89f719867a 100644
--- a/src/libponyc/codegen/gencall.c
+++ b/src/libponyc/codegen/gencall.c
@@ -13,8 +13,8 @@
 #include "../ast/stringtab.h"
 #include "../../libponyrt/mem/pool.h"
 #include "../../libponyrt/mem/heap.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 static LLVMValueRef invoke_fun(compile_t* c, LLVMValueRef fun,
   LLVMValueRef* args, int count, const char* ret, bool setcc)
@@ -227,7 +227,7 @@ static LLVMValueRef dispatch_function(compile_t* c, reach_type_t* t,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -303,7 +303,7 @@ static void set_method_external_interface(reach_type_t* t, const char* name)
 
 LLVMValueRef gen_funptr(compile_t* c, ast_t* ast)
 {
-  assert((ast_id(ast) == TK_FUNREF) || (ast_id(ast) == TK_BEREF));
+  pony_assert((ast_id(ast) == TK_FUNREF) || (ast_id(ast) == TK_BEREF));
   AST_GET_CHILDREN(ast, receiver, method);
   ast_t* typeargs = NULL;
 
@@ -325,7 +325,7 @@ LLVMValueRef gen_funptr(compile_t* c, ast_t* ast)
   // Get the receiver type.
   ast_t* type = ast_type(receiver);
   reach_type_t* t = reach_type(c->reach, type);
-  assert(t != NULL);
+  pony_assert(t != NULL);
 
   const char* name = ast_name(method);
   token_id cap = cap_dispatch(type);
@@ -351,7 +351,7 @@ LLVMValueRef gen_funptr(compile_t* c, ast_t* ast)
         set_method_external_interface(t, name);
         break;
       default:
-        assert(0);
+        pony_assert(0);
         break;
     }
   }
@@ -446,7 +446,7 @@ static void tuple_indices_push(call_tuple_indices_t* ti, size_t idx)
 
 static size_t tuple_indices_pop(call_tuple_indices_t* ti)
 {
-  assert(ti->count > 0);
+  pony_assert(ti->count > 0);
 
   return ti->data[--ti->count];
 }
@@ -509,7 +509,7 @@ static bool can_inline_message_send(reach_type_t* t, reach_method_t* m,
       return false;
     }
 
-    assert(param_count == m_sub->param_count);
+    pony_assert(param_count == m_sub->param_count);
     for(size_t i = 0; i < param_count; i++)
     {
       // If the param is a boxable type for us and an unboxable type for one of
@@ -561,7 +561,7 @@ LLVMValueRef gen_call(compile_t* c, ast_t* ast)
   const char* method_name = ast_name(method);
   ast_t* type = ast_type(receiver);
   reach_type_t* t = reach_type(c->reach, type);
-  assert(t != NULL);
+  pony_assert(t != NULL);
 
   // Generate the arguments.
   size_t count = ast_childcount(positional) + 1;
@@ -667,7 +667,7 @@ LLVMValueRef gen_call(compile_t* c, ast_t* ast)
         break;
 
       default:
-        assert(0);
+        pony_assert(0);
         return NULL;
     }
   } else {
@@ -828,7 +828,7 @@ LLVMValueRef gen_pattern_eq(compile_t* c, ast_t* pattern, LLVMValueRef r_value)
   // Generate the receiver.
   LLVMValueRef l_value = gen_expr(c, pattern);
   reach_type_t* t = reach_type(c->reach, pattern_type);
-  assert(t != NULL);
+  pony_assert(t != NULL);
 
   // Static or virtual dispatch.
   token_id cap = cap_dispatch(pattern_type);
@@ -893,7 +893,7 @@ static LLVMValueRef declare_ffi(compile_t* c, const char* f_name,
       p_type = ast_childidx(arg, 1);
 
     reach_type_t* pt = reach_type(c->reach, p_type);
-    assert(pt != NULL);
+    pony_assert(pt != NULL);
 
     // An intrinsic that takes a Bool should be i1, not ibool.
     if(intrinsic && is_bool(pt->ast))
@@ -1007,7 +1007,7 @@ LLVMValueRef gen_ffi(compile_t* c, ast_t* ast)
   // Get the return type.
   ast_t* type = ast_type(ast);
   reach_type_t* t = reach_type(c->reach, type);
-  assert(t != NULL);
+  pony_assert(t != NULL);
 
   // Get the function.
   LLVMValueRef func = LLVMGetNamedFunction(c->module, f_name);
diff --git a/src/libponyc/codegen/gencontrol.c b/src/libponyc/codegen/gencontrol.c
index 696ecf3ce6f..bffd59d2165 100644
--- a/src/libponyc/codegen/gencontrol.c
+++ b/src/libponyc/codegen/gencontrol.c
@@ -5,7 +5,7 @@
 #include "../pass/expr.h"
 #include "../type/subtype.h"
 #include "../../libponyrt/mem/pool.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 
 LLVMValueRef gen_seq(compile_t* c, ast_t* ast)
@@ -549,7 +549,7 @@ LLVMValueRef gen_try(compile_t* c, ast_t* ast)
   // This backwards-incompatible API change to LLVMBuildLandingPad is only in
   // LLVM 3.7.0. In 3.7.1 and all later versions, backward-compatibility was
   // restored.
-  assert((c->frame->fun != NULL) && "No function in current frame!");
+  pony_assert((c->frame->fun != NULL) && "No function in current frame!");
   LLVMSetPersonalityFn(c->frame->fun, c->personality);
   LLVMValueRef landing = LLVMBuildLandingPad(c->builder, lp_type, 1, "");
 #else
diff --git a/src/libponyc/codegen/gendesc.c b/src/libponyc/codegen/gendesc.c
index 86a51261028..6ea661dc956 100644
--- a/src/libponyc/codegen/gendesc.c
+++ b/src/libponyc/codegen/gendesc.c
@@ -4,8 +4,8 @@
 #include "../type/reify.h"
 #include "../ast/stringtab.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 #define DESC_ID 0
 #define DESC_SIZE 1
@@ -308,8 +308,8 @@ static LLVMValueRef make_vtable(compile_t* c, reach_type_t* t)
     while((m = reach_mangled_next(&n->r_mangled, &j)) != NULL)
     {
       uint32_t index = m->vtable_index;
-      assert(index != (uint32_t)-1);
-      assert(vtable[index] == NULL);
+      pony_assert(index != (uint32_t)-1);
+      pony_assert(vtable[index] == NULL);
 
       if(t->primitive != NULL)
         vtable[index] = make_unbox_function(c, t, m);
@@ -604,7 +604,7 @@ LLVMValueRef gendesc_isnominal(compile_t* c, LLVMValueRef desc, ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return GEN_NOVALUE;
 }
 
@@ -612,7 +612,7 @@ LLVMValueRef gendesc_istrait(compile_t* c, LLVMValueRef desc, ast_t* type)
 {
   // Get the trait identifier.
   reach_type_t* t = reach_type(c->reach, type);
-  assert(t != NULL);
+  pony_assert(t != NULL);
   LLVMValueRef trait_id = LLVMConstInt(c->i32, t->type_id, false);
 
   // Read the count and the trait list from the descriptor.
diff --git a/src/libponyc/codegen/genexe.c b/src/libponyc/codegen/genexe.c
index f6f7451c8cf..5feb6e24604 100644
--- a/src/libponyc/codegen/genexe.c
+++ b/src/libponyc/codegen/genexe.c
@@ -11,8 +11,8 @@
 #include "../type/assemble.h"
 #include "../type/lookup.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 #ifdef PLATFORM_IS_POSIX_BASED
 #  include <unistd.h>
diff --git a/src/libponyc/codegen/genexpr.c b/src/libponyc/codegen/genexpr.c
index 27635a9dfb0..a8e4625d828 100644
--- a/src/libponyc/codegen/genexpr.c
+++ b/src/libponyc/codegen/genexpr.c
@@ -9,7 +9,7 @@
 #include "gencall.h"
 #include "../type/subtype.h"
 #include "../../libponyrt/mem/pool.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 LLVMValueRef gen_expr(compile_t* c, ast_t* ast)
 {
@@ -97,7 +97,7 @@ LLVMValueRef gen_expr(compile_t* c, ast_t* ast)
         case TK_PARAMREF:
           break;
         default:
-          assert(0);
+          pony_assert(0);
           break;
       }
       break;
@@ -209,7 +209,7 @@ static LLVMValueRef assign_to_tuple(compile_t* c, LLVMTypeRef l_type,
   LLVMValueRef r_value, ast_t* type)
 {
   // Cast each component.
-  assert(ast_id(type) == TK_TUPLETYPE);
+  pony_assert(ast_id(type) == TK_TUPLETYPE);
 
   int count = LLVMCountStructElementTypes(l_type);
   size_t buf_size = count * sizeof(LLVMTypeRef);
@@ -265,7 +265,7 @@ LLVMValueRef gen_assign_cast(compile_t* c, LLVMTypeRef l_type,
       if((r_type == c->i1) && (l_type == c->ibool))
         return LLVMBuildZExt(c->builder, r_value, l_type, "");
 
-      assert(LLVMGetTypeKind(r_type) == LLVMPointerTypeKind);
+      pony_assert(LLVMGetTypeKind(r_type) == LLVMPointerTypeKind);
       return gen_unbox(c, type, r_value);
     }
 
@@ -284,7 +284,7 @@ LLVMValueRef gen_assign_cast(compile_t* c, LLVMTypeRef l_type,
       if(LLVMGetTypeKind(r_type) == LLVMPointerTypeKind)
       {
         r_value = gen_unbox(c, type, r_value);
-        assert(LLVMGetTypeKind(LLVMTypeOf(r_value)) == LLVMStructTypeKind);
+        pony_assert(LLVMGetTypeKind(LLVMTypeOf(r_value)) == LLVMStructTypeKind);
       }
 
       return assign_to_tuple(c, l_type, r_value, type);
@@ -293,6 +293,6 @@ LLVMValueRef gen_assign_cast(compile_t* c, LLVMTypeRef l_type,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
diff --git a/src/libponyc/codegen/genfun.c b/src/libponyc/codegen/genfun.c
index a0532ddc102..d432c7133c0 100644
--- a/src/libponyc/codegen/genfun.c
+++ b/src/libponyc/codegen/genfun.c
@@ -13,8 +13,8 @@
 #include "../../libponyrt/ds/fun.h"
 #include "../../libponyrt/mem/pool.h"
 #include "../../libponyrt/mem/heap.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 static void name_param(compile_t* c, reach_type_t* t,
   reach_method_t* m, LLVMValueRef func, const char* name, unsigned index,
@@ -169,7 +169,7 @@ static void make_prototype(compile_t* c, reach_type_t* t,
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return;
   }
 
@@ -221,7 +221,7 @@ static void make_prototype(compile_t* c, reach_type_t* t,
   {
     // Store the finaliser and use the C calling convention and an external
     // linkage.
-    assert(t->final_fn == NULL);
+    pony_assert(t->final_fn == NULL);
     t->final_fn = m->func;
     LLVMSetFunctionCallConv(m->func, LLVMCCallConv);
     LLVMSetLinkage(m->func, LLVMExternalLinkage);
@@ -320,7 +320,7 @@ static void call_embed_finalisers(compile_t* c, reach_type_t* t,
 
 static bool genfun_fun(compile_t* c, reach_type_t* t, reach_method_t* m)
 {
-  assert(m->func != NULL);
+  pony_assert(m->func != NULL);
 
   AST_GET_CHILDREN(m->r_fun, cap, id, typeparams, params, result, can_error,
     body);
@@ -365,8 +365,8 @@ static bool genfun_fun(compile_t* c, reach_type_t* t, reach_method_t* m)
 
 static bool genfun_be(compile_t* c, reach_type_t* t, reach_method_t* m)
 {
-  assert(m->func != NULL);
-  assert(m->func_handler != NULL);
+  pony_assert(m->func != NULL);
+  pony_assert(m->func_handler != NULL);
 
   AST_GET_CHILDREN(m->r_fun, cap, id, typeparams, params, result, can_error,
     body);
@@ -411,7 +411,7 @@ static bool genfun_be(compile_t* c, reach_type_t* t, reach_method_t* m)
 
 static bool genfun_new(compile_t* c, reach_type_t* t, reach_method_t* m)
 {
-  assert(m->func != NULL);
+  pony_assert(m->func != NULL);
 
   AST_GET_CHILDREN(m->r_fun, cap, id, typeparams, params, result, can_error,
     body);
@@ -442,8 +442,8 @@ static bool genfun_new(compile_t* c, reach_type_t* t, reach_method_t* m)
 
 static bool genfun_newbe(compile_t* c, reach_type_t* t, reach_method_t* m)
 {
-  assert(m->func != NULL);
-  assert(m->func_handler != NULL);
+  pony_assert(m->func != NULL);
+  pony_assert(m->func_handler != NULL);
 
   AST_GET_CHILDREN(m->r_fun, cap, id, typeparams, params, result, can_error,
     body);
@@ -553,7 +553,7 @@ static bool genfun_allocator(compile_t* c, reach_type_t* t)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -565,11 +565,11 @@ static bool genfun_allocator(compile_t* c, reach_type_t* t)
 static bool genfun_forward(compile_t* c, reach_type_t* t,
   reach_method_name_t* n,  reach_method_t* m)
 {
-  assert(m->func != NULL);
+  pony_assert(m->func != NULL);
 
   reach_method_t* m2 = reach_method(t, m->cap, n->name, m->typeargs);
-  assert(m2 != NULL);
-  assert(m2 != m);
+  pony_assert(m2 != NULL);
+  pony_assert(m2 != m);
 
   codegen_startfun(c, m->func, m->di_file, m->di_method);
 
@@ -656,7 +656,7 @@ void genfun_param_attrs(compile_t* c, reach_type_t* t, reach_method_t* m,
 #endif
             break;
           default:
-            assert(0);
+            pony_assert(0);
         }
       }
     }
@@ -744,7 +744,7 @@ bool genfun_method_bodies(compile_t* c, reach_type_t* t)
             break;
 
           default:
-            assert(0);
+            pony_assert(0);
             return false;
         }
       }
diff --git a/src/libponyc/codegen/genheader.c b/src/libponyc/codegen/genheader.c
index 35e7e46eabe..6ae10fc17c2 100644
--- a/src/libponyc/codegen/genheader.c
+++ b/src/libponyc/codegen/genheader.c
@@ -6,8 +6,8 @@
 #include "../type/reify.h"
 #include "../ast/printbuf.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 static const char* c_type_name(compile_t* c, const char* name)
 {
diff --git a/src/libponyc/codegen/genident.c b/src/libponyc/codegen/genident.c
index 3d0fb25e1c2..21289ebaf1d 100644
--- a/src/libponyc/codegen/genident.c
+++ b/src/libponyc/codegen/genident.c
@@ -1,7 +1,7 @@
 #include "genident.h"
 #include "gendesc.h"
 #include "genexpr.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static LLVMValueRef gen_is_value(compile_t* c, ast_t* left_type,
   ast_t* right_type, LLVMValueRef l_value, LLVMValueRef r_value);
@@ -9,9 +9,9 @@ static LLVMValueRef gen_is_value(compile_t* c, ast_t* left_type,
 static LLVMValueRef tuple_is(compile_t* c, ast_t* left_type, ast_t* right_type,
   LLVMValueRef l_value, LLVMValueRef r_value)
 {
-  assert(ast_id(left_type) == TK_TUPLETYPE);
-  assert(ast_id(right_type) == TK_TUPLETYPE);
-  assert(ast_childcount(left_type) == ast_childcount(right_type));
+  pony_assert(ast_id(left_type) == TK_TUPLETYPE);
+  pony_assert(ast_id(right_type) == TK_TUPLETYPE);
+  pony_assert(ast_childcount(left_type) == ast_childcount(right_type));
 
   // Pairwise comparison.
   LLVMBasicBlockRef this_block = LLVMGetInsertBlock(c->builder);
@@ -115,7 +115,7 @@ static LLVMValueRef gen_is_value(compile_t* c, ast_t* left_type,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
diff --git a/src/libponyc/codegen/genmatch.c b/src/libponyc/codegen/genmatch.c
index 1fef33ba0c4..61c2833684c 100644
--- a/src/libponyc/codegen/genmatch.c
+++ b/src/libponyc/codegen/genmatch.c
@@ -11,7 +11,7 @@
 #include "../type/alias.h"
 #include "../type/viewpoint.h"
 #include "../type/lookup.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 typedef enum
 {
@@ -231,7 +231,7 @@ static bool check_type(compile_t* c, LLVMValueRef ptr, LLVMValueRef desc,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -328,7 +328,7 @@ static bool dynamic_tuple_ptr(compile_t* c, LLVMValueRef ptr,
 
   for(int i = 0; pattern_child != NULL; i++)
   {
-    assert(ast_id(pattern_child) == TK_SEQ);
+    pony_assert(ast_id(pattern_child) == TK_SEQ);
 
     // Skip over the SEQ node.
     ast_t* pattern_expr = ast_child(pattern_child);
@@ -537,7 +537,7 @@ static bool static_tuple_from_tuple(compile_t* c, LLVMValueRef value,
   // The match expression is a tuple. The type checker will have made sure
   // it's the right cardinality and each element has a useful type relation
   // with the pattern.
-  assert(LLVMGetTypeKind(LLVMTypeOf(value)) == LLVMStructTypeKind);
+  pony_assert(LLVMGetTypeKind(LLVMTypeOf(value)) == LLVMStructTypeKind);
 
   // We have a static type.
   ast_t* type_child = ast_child(type);
@@ -546,7 +546,7 @@ static bool static_tuple_from_tuple(compile_t* c, LLVMValueRef value,
   // Destructure the tuple and continue pattern matching on each element.
   for(int i = 0; pattern_child != NULL; i++)
   {
-    assert(ast_id(pattern_child) == TK_SEQ);
+    pony_assert(ast_id(pattern_child) == TK_SEQ);
 
     // Skip over the SEQ node.
     ast_t* pattern_expr = ast_child(pattern_child);
@@ -559,7 +559,7 @@ static bool static_tuple_from_tuple(compile_t* c, LLVMValueRef value,
     pattern_child = ast_sibling(pattern_child);
   }
 
-  assert(type_child == NULL);
+  pony_assert(type_child == NULL);
   return true;
 }
 
@@ -601,7 +601,7 @@ static bool static_value(compile_t* c, LLVMValueRef value, ast_t* type,
   if(!is_subtype(type, param_type, NULL, c->opt))
   {
     // Switch to dynamic value checking.
-    assert(LLVMTypeOf(value) == c->object_ptr);
+    pony_assert(LLVMTypeOf(value) == c->object_ptr);
     LLVMValueRef desc = gendesc_fetch(c, value);
     return dynamic_value_object(c, value, desc, pattern, next_block);
   }
@@ -625,7 +625,7 @@ static bool static_capture(compile_t* c, LLVMValueRef value, ast_t* type,
   if(!is_subtype(type, pattern_type, NULL, c->opt))
   {
     // Switch to dynamic capture.
-    assert(LLVMTypeOf(value) == c->object_ptr);
+    pony_assert(LLVMTypeOf(value) == c->object_ptr);
     LLVMValueRef desc = gendesc_fetch(c, value);
     return dynamic_capture_object(c, value, desc, pattern, next_block);
   }
@@ -654,8 +654,8 @@ static bool static_match(compile_t* c, LLVMValueRef value, ast_t* type,
       // during type checking.
       ast_t* child = ast_child(pattern);
 
-      assert(child != NULL);
-      assert(ast_sibling(child) == NULL);
+      pony_assert(child != NULL);
+      pony_assert(ast_sibling(child) == NULL);
 
       // Pass on the element in the seq instead of the seq.
       return static_match(c, value, type, child, next_block);
@@ -664,8 +664,8 @@ static bool static_match(compile_t* c, LLVMValueRef value, ast_t* type,
     case TK_TUPLE:
     {
       // Tuples must have multiple elements, or they aren't tuples.
-      assert(ast_child(pattern) != NULL);
-      assert(ast_sibling(ast_child(pattern)) != NULL);
+      pony_assert(ast_child(pattern) != NULL);
+      pony_assert(ast_sibling(ast_child(pattern)) != NULL);
 
       // Destructure the match expression (or element thereof).
       return static_tuple(c, value, type, pattern, next_block);
diff --git a/src/libponyc/codegen/genname.c b/src/libponyc/codegen/genname.c
index 5603cbae864..a34728fe9e1 100644
--- a/src/libponyc/codegen/genname.c
+++ b/src/libponyc/codegen/genname.c
@@ -3,8 +3,8 @@
 #include "../ast/stringtab.h"
 #include "../ast/lexer.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 static void types_append(printbuf_t* buf, ast_t* elements);
 
@@ -60,7 +60,7 @@ static void type_append(printbuf_t* buf, ast_t* type, bool first)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
 }
 
 static void types_append(printbuf_t* buf, ast_t* elements)
@@ -91,7 +91,7 @@ static const char* stringtab_two(const char* a, const char* b)
   if(a == NULL)
     a = "_";
 
-  assert(b != NULL);
+  pony_assert(b != NULL);
   printbuf_t* buf = printbuf_new();
   printbuf(buf, "%s_%s", a, b);
   return stringtab_buf(buf);
diff --git a/src/libponyc/codegen/genoperator.c b/src/libponyc/codegen/genoperator.c
index 4eb1ee1c929..f98edfa967d 100644
--- a/src/libponyc/codegen/genoperator.c
+++ b/src/libponyc/codegen/genoperator.c
@@ -6,7 +6,7 @@
 #include "gentype.h"
 #include "../pkg/platformfuns.h"
 #include "../type/subtype.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 typedef LLVMValueRef (*const_binop)(LLVMValueRef left, LLVMValueRef right);
 
@@ -396,7 +396,7 @@ static bool assign_tuple(compile_t* c, ast_t* left, ast_t* r_type,
         break;
 
       default:
-        assert(0);
+        pony_assert(0);
     }
 
     if(expr != NULL)
@@ -415,7 +415,7 @@ static bool assign_tuple(compile_t* c, ast_t* left, ast_t* r_type,
     rtype_child = ast_sibling(rtype_child);
   }
 
-  assert(rtype_child == NULL);
+  pony_assert(rtype_child == NULL);
   return true;
 }
 
@@ -428,7 +428,7 @@ static LLVMValueRef assign_rvalue(compile_t* c, ast_t* left, ast_t* r_type,
       // The actual expression is inside a sequence node.
       while(ast_id(left) == TK_SEQ)
       {
-        assert(ast_childcount(left) == 1);
+        pony_assert(ast_childcount(left) == 1);
         left = ast_child(left);
       }
       return assign_rvalue(c, left, r_type, r_value);
@@ -509,7 +509,7 @@ static LLVMValueRef assign_rvalue(compile_t* c, ast_t* left, ast_t* r_type,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -650,7 +650,7 @@ LLVMValueRef gen_shl(compile_t* c, ast_t* left, ast_t* right, bool safe)
     return NULL;
 
   LLVMTypeRef l_type = LLVMTypeOf(l_value);
-  assert(LLVMGetTypeKind(l_type) == LLVMIntegerTypeKind);
+  pony_assert(LLVMGetTypeKind(l_type) == LLVMIntegerTypeKind);
   unsigned width = LLVMGetIntTypeWidth(l_type);
 
   if(LLVMIsConstant(r_value))
@@ -703,7 +703,7 @@ LLVMValueRef gen_shr(compile_t* c, ast_t* left, ast_t* right, bool safe)
     return NULL;
 
   LLVMTypeRef l_type = LLVMTypeOf(l_value);
-  assert(LLVMGetTypeKind(l_type) == LLVMIntegerTypeKind);
+  pony_assert(LLVMGetTypeKind(l_type) == LLVMIntegerTypeKind);
   unsigned width = LLVMGetIntTypeWidth(l_type);
 
   if(LLVMIsConstant(r_value))
diff --git a/src/libponyc/codegen/genopt.cc b/src/libponyc/codegen/genopt.cc
index 6c8dfa0d1a3..9a4361090f3 100644
--- a/src/libponyc/codegen/genopt.cc
+++ b/src/libponyc/codegen/genopt.cc
@@ -31,6 +31,7 @@
 #include <llvm/ADT/SmallSet.h>
 
 #include "../../libponyrt/mem/heap.h"
+#include "ponyassert.h"
 
 #ifdef _MSC_VER
 #  pragma warning(pop)
@@ -467,7 +468,7 @@ class DispatchPonyCtx : public FunctionPass
     if(name.size() < 10 || name.rfind("_Dispatch") != name.size() - 9)
       return false;
 
-    assert(f.arg_size() > 0);
+    pony_assert(f.arg_size() > 0);
 
     Value* ctx = &(*f.arg_begin());
 
diff --git a/src/libponyc/codegen/genprim.c b/src/libponyc/codegen/genprim.c
index efdd9c3670e..954d20e7635 100644
--- a/src/libponyc/codegen/genprim.c
+++ b/src/libponyc/codegen/genprim.c
@@ -10,8 +10,8 @@
 #include "../type/assemble.h"
 #include "../type/cap.h"
 #include "../../libponyrt/mem/heap.h"
+#include "ponyassert.h"
 
-#include <assert.h>
 #include <string.h>
 
 #define FIND_METHOD(name, cap) \
@@ -1707,7 +1707,7 @@ static void number_conversions(compile_t* c)
   else if(target_is_llp64(c->opt->triple))
     conv = llp64_conv;
 
-  assert(conv != NULL);
+  pony_assert(conv != NULL);
 
   void* data[3];
   data[2] = (void*)target_is_native128(c->opt->triple);
diff --git a/src/libponyc/codegen/genreference.c b/src/libponyc/codegen/genreference.c
index 337bd88846a..edec176c2d8 100644
--- a/src/libponyc/codegen/genreference.c
+++ b/src/libponyc/codegen/genreference.c
@@ -7,8 +7,8 @@
 #include "../type/cap.h"
 #include "../type/subtype.h"
 #include "../type/viewpoint.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 LLVMValueRef gen_this(compile_t* c, ast_t* ast)
 {
@@ -31,7 +31,7 @@ static LLVMValueRef make_fieldptr(compile_t* c, LLVMValueRef l_value,
   {
     case TK_NOMINAL:
     {
-      assert(ast_id(right) == TK_ID);
+      pony_assert(ast_id(right) == TK_ID);
 
       ast_t* def = (ast_t*)ast_data(l_type);
       ast_t* field = ast_get(def, ast_name(right), NULL);
@@ -48,7 +48,7 @@ static LLVMValueRef make_fieldptr(compile_t* c, LLVMValueRef l_value,
 
     case TK_TUPLETYPE:
     {
-      assert(ast_id(right) == TK_INT);
+      pony_assert(ast_id(right) == TK_INT);
       int index = (int)ast_int(right)->low;
 
       return LLVMBuildExtractValue(c->builder, l_value, index, "");
@@ -60,7 +60,7 @@ static LLVMValueRef make_fieldptr(compile_t* c, LLVMValueRef l_value,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -87,7 +87,7 @@ LLVMValueRef gen_fieldload(compile_t* c, ast_t* ast)
   if(field == NULL)
     return NULL;
 
-  assert((ast_id(l_type) == TK_NOMINAL) || (ast_id(l_type) == TK_TUPLETYPE));
+  pony_assert((ast_id(l_type) == TK_NOMINAL) || (ast_id(l_type) == TK_TUPLETYPE));
 
   // Don't load if we're reading from a tuple.
   if(ast_id(l_type) != TK_TUPLETYPE)
@@ -202,7 +202,7 @@ LLVMValueRef gen_localptr(compile_t* c, ast_t* ast)
   const char* name = ast_name(id);
 
   LLVMValueRef value = codegen_getlocal(c, name);
-  assert(value != NULL);
+  pony_assert(value != NULL);
 
   return value;
 }
@@ -236,7 +236,7 @@ LLVMValueRef gen_addressof(compile_t* c, ast_t* ast)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -292,7 +292,7 @@ static LLVMValueRef gen_digestof_value(compile_t* c, LLVMValueRef value)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
diff --git a/src/libponyc/codegen/gentrace.c b/src/libponyc/codegen/gentrace.c
index ddb27ebaeea..446d0f7c10a 100644
--- a/src/libponyc/codegen/gentrace.c
+++ b/src/libponyc/codegen/gentrace.c
@@ -6,7 +6,7 @@
 #include "../type/cap.h"
 #include "../type/matchtype.h"
 #include "../type/subtype.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 // Arranged from most specific to least specific.
 typedef enum
@@ -67,7 +67,7 @@ static trace_t trace_union_machine_word(trace_t a)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return TRACE_NONE;
 }
 
@@ -98,7 +98,7 @@ static trace_t trace_union_primitive(trace_t a)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return TRACE_NONE;
 }
 
@@ -123,7 +123,7 @@ static trace_t trace_union_val(trace_t a)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return TRACE_NONE;
 }
 
@@ -148,7 +148,7 @@ static trace_t trace_union_mut(trace_t a)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return TRACE_NONE;
 }
 
@@ -173,7 +173,7 @@ static trace_t trace_union_tag(trace_t a)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return TRACE_NONE;
 }
 
@@ -195,7 +195,7 @@ static trace_t trace_type_union(ast_t* type)
 
       case TRACE_MAYBE:
         // Can't be in a union.
-        assert(0);
+        pony_assert(0);
         return TRACE_NONE;
 
       case TRACE_MACHINE_WORD:
@@ -227,7 +227,7 @@ static trace_t trace_type_union(ast_t* type)
 
       case TRACE_STATIC:
         // Can't happen here.
-        assert(0);
+        pony_assert(0);
         return TRACE_DYNAMIC;
     }
   }
@@ -250,7 +250,7 @@ static trace_t trace_type_isect(ast_t* type)
       case TRACE_NONE:
       case TRACE_MAYBE:
         // Can't be in an isect.
-        assert(0);
+        pony_assert(0);
         return TRACE_NONE;
 
       case TRACE_PRIMITIVE:
@@ -280,7 +280,7 @@ static trace_t trace_type_isect(ast_t* type)
 
       case TRACE_STATIC:
         // Can't happen here.
-        assert(0);
+        pony_assert(0);
         break;
     }
   }
@@ -339,7 +339,7 @@ static trace_t trace_type_nominal(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return TRACE_NONE;
 }
 
@@ -362,7 +362,7 @@ static trace_t trace_type(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return TRACE_DYNAMIC;
 }
 
@@ -453,11 +453,11 @@ static trace_t trace_type_dst_cap(trace_t src_trace, trace_t dst_trace,
 
     case TRACE_STATIC:
       // Can't happen here.
-      assert(0);
+      pony_assert(0);
       return src_trace;
 
     default:
-      assert(0);
+      pony_assert(0);
       return src_trace;
   }
 }
@@ -509,7 +509,7 @@ static void trace_unknown(compile_t* c, LLVMValueRef ctx, LLVMValueRef object,
 static int trace_cap_nominal(pass_opt_t* opt, ast_t* type, ast_t* orig,
   ast_t* tuple)
 {
-  assert(ast_id(type) == TK_NOMINAL);
+  pony_assert(ast_id(type) == TK_NOMINAL);
 
   ast_t* cap = cap_fetch(type);
 
@@ -559,7 +559,7 @@ static int trace_cap_nominal(pass_opt_t* opt, ast_t* type, ast_t* orig,
     }
   }
 
-  assert(ast_id(cap) == TK_TAG);
+  pony_assert(ast_id(cap) == TK_TAG);
 
   int ret = -1;
   if(is_matchtype(orig, type, opt) == MATCHTYPE_ACCEPT)
@@ -572,10 +572,10 @@ static int trace_cap_nominal(pass_opt_t* opt, ast_t* type, ast_t* orig,
 static void trace_static(compile_t* c, LLVMValueRef ctx, LLVMValueRef object,
   ast_t* src_type, ast_t* dst_type)
 {
-  assert(ast_id(src_type) == TK_NOMINAL);
+  pony_assert(ast_id(src_type) == TK_NOMINAL);
 
   int mutability = trace_cap_nominal(c->opt, src_type, dst_type, NULL);
-  assert(mutability != -1);
+  pony_assert(mutability != -1);
 
   if(is_known(src_type))
     trace_known(c, ctx, object, src_type, mutability);
@@ -602,13 +602,13 @@ static void trace_tuple(compile_t* c, LLVMValueRef ctx, LLVMValueRef src_value,
       src_child = ast_sibling(src_child);
       dst_child = ast_sibling(dst_child);
     }
-    assert(src_child == NULL && dst_child == NULL);
+    pony_assert(src_child == NULL && dst_child == NULL);
   } else {
     // This is a boxed tuple. Trace the box, then handle the elements.
     trace_unknown(c, ctx, dst_value, PONY_TRACE_OPAQUE);
 
     // Extract the elements from the original unboxed tuple.
-    assert(LLVMGetTypeKind(LLVMTypeOf(src_value)) == LLVMStructTypeKind);
+    pony_assert(LLVMGetTypeKind(LLVMTypeOf(src_value)) == LLVMStructTypeKind);
 
     ast_t* src_child = ast_child(src_type);
     while(src_child != NULL)
@@ -765,7 +765,7 @@ static void trace_dynamic_nominal(compile_t* c, LLVMValueRef ctx,
   LLVMValueRef object, ast_t* type, ast_t* orig, ast_t* tuple,
   LLVMBasicBlockRef next_block)
 {
-  assert(ast_id(type) == TK_NOMINAL);
+  pony_assert(ast_id(type) == TK_NOMINAL);
 
   // Skip if a primitive.
   ast_t* def = (ast_t*)ast_data(type);
@@ -860,7 +860,7 @@ bool gentrace_needed(compile_t* c, ast_t* src_type, ast_t* dst_type)
   switch(trace_type(src_type))
   {
     case TRACE_NONE:
-      assert(0);
+      pony_assert(0);
       return false;
 
     case TRACE_MACHINE_WORD:
@@ -890,7 +890,7 @@ bool gentrace_needed(compile_t* c, ast_t* src_type, ast_t* dst_type)
           src_child = ast_sibling(src_child);
           dst_child = ast_sibling(dst_child);
         }
-        assert(src_child == NULL && dst_child == NULL);
+        pony_assert(src_child == NULL && dst_child == NULL);
       } else {
         // This is a boxed tuple. We'll have to trace the box anyway.
         return true;
@@ -949,7 +949,7 @@ void gentrace(compile_t* c, LLVMValueRef ctx, LLVMValueRef src_value,
   switch(trace_method)
   {
     case TRACE_NONE:
-      assert(0);
+      pony_assert(0);
       return;
 
     case TRACE_MACHINE_WORD:
diff --git a/src/libponyc/codegen/gentype.c b/src/libponyc/codegen/gentype.c
index 529355a4607..68787c1e17c 100644
--- a/src/libponyc/codegen/gentype.c
+++ b/src/libponyc/codegen/gentype.c
@@ -12,9 +12,9 @@
 #include "../type/reify.h"
 #include "../type/subtype.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdlib.h>
 #include <string.h>
-#include <assert.h>
 
 static size_t tbaa_metadata_hash(tbaa_metadata_t* a)
 {
@@ -45,7 +45,7 @@ void tbaa_metadatas_free(tbaa_metadatas_t* tbaa_mds)
 
 LLVMValueRef tbaa_metadata_for_type(compile_t* c, ast_t* type)
 {
-  assert(ast_id(type) == TK_NOMINAL);
+  pony_assert(ast_id(type) == TK_NOMINAL);
 
   const char* name = genname_type_and_cap(type);
   tbaa_metadata_t k;
@@ -250,7 +250,7 @@ static bool make_opaque_struct(compile_t* c, reach_type_t* t)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -331,7 +331,7 @@ static void make_debug_info(compile_t* c, reach_type_t* t)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
 }
 
 static void make_box_type(compile_t* c, reach_type_t* t)
@@ -459,7 +459,7 @@ static bool make_struct(compile_t* c, reach_type_t* t)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -483,7 +483,7 @@ static bool make_struct(compile_t* c, reach_type_t* t)
 
     if(elements[i + extra] == NULL)
     {
-      assert(0);
+      pony_assert(0);
       return false;
     }
   }
@@ -619,7 +619,7 @@ static void make_debug_final(compile_t* c, reach_type_t* t)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
 }
 
 static void make_intrinsic_methods(compile_t* c, reach_type_t* t)
@@ -760,7 +760,7 @@ bool gentypes(compile_t* c)
   // Cache the instance of None, which is used as the return value for
   // behaviour calls.
   t = reach_type_name(c->reach, "None");
-  assert(t != NULL);
+  pony_assert(t != NULL);
   c->none_instance = t->instance;
 
   if(c->opt->verbosity >= VERBOSITY_INFO)
diff --git a/src/libponyc/codegen/host.cc b/src/libponyc/codegen/host.cc
index 9f10e08827e..1e22f60db24 100644
--- a/src/libponyc/codegen/host.cc
+++ b/src/libponyc/codegen/host.cc
@@ -25,6 +25,7 @@
 
 #include <stdio.h>
 #include "codegen.h"
+#include "ponyassert.h"
 
 using namespace llvm;
 
@@ -37,7 +38,7 @@ char* LLVMGetHostCPUFeatures()
 {
   StringMap<bool> features;
   bool got_features = sys::getHostCPUFeatures(features);
-  assert(got_features);
+  pony_assert(got_features);
   (void)got_features;
 
   // Calculate the size of buffer that will be needed to return all features.
@@ -46,7 +47,7 @@ char* LLVMGetHostCPUFeatures()
     buf_size += (*it).getKey().str().length() + 2; // plus +/- char and ,/null
 
   char* buf = (char*)malloc(buf_size);
-  assert(buf != NULL);
+  pony_assert(buf != NULL);
   buf[0] = 0;
 
   for(auto it = features.begin(); it != features.end();)
@@ -123,7 +124,7 @@ void LLVMSetCallInaccessibleMemOnly(LLVMValueRef inst)
     c->addAttribute(AttributeSet::FunctionIndex,
       Attribute::InaccessibleMemOnly);
   else
-    assert(0);
+    pony_assert(0);
 }
 
 void LLVMSetInaccessibleMemOrArgMemOnly(LLVMValueRef fun)
@@ -141,7 +142,7 @@ void LLVMSetCallInaccessibleMemOrArgMemOnly(LLVMValueRef inst)
     c->addAttribute(AttributeSet::FunctionIndex,
       Attribute::InaccessibleMemOrArgMemOnly);
   else
-    assert(0);
+    pony_assert(0);
 }
 #  endif
 #endif
@@ -187,7 +188,7 @@ LLVMModuleRef LLVMParseIRFileInContext(LLVMContextRef ctx, const char* file)
 static MDNode* extractMDNode(MetadataAsValue* mdv)
 {
   Metadata* md = mdv->getMetadata();
-  assert(isa<MDNode>(md) || isa<ConstantAsMetadata>(md));
+  pony_assert(isa<MDNode>(md) || isa<ConstantAsMetadata>(md));
 
   MDNode* n = dyn_cast<MDNode>(md);
   if(n != NULL)
@@ -198,7 +199,7 @@ static MDNode* extractMDNode(MetadataAsValue* mdv)
 
 void LLVMSetMetadataStr(LLVMValueRef inst, const char* str, LLVMValueRef node)
 {
-  assert(node != NULL);
+  pony_assert(node != NULL);
 
   MDNode* n = extractMDNode(unwrap<MetadataAsValue>(node));
 
diff --git a/src/libponyc/expr/call.c b/src/libponyc/expr/call.c
index fc2ab059684..603bf9b239a 100644
--- a/src/libponyc/expr/call.c
+++ b/src/libponyc/expr/call.c
@@ -15,7 +15,7 @@
 #include "../type/sanitise.h"
 #include "../type/subtype.h"
 #include "../type/viewpoint.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static bool insert_apply(pass_opt_t* opt, ast_t** astp)
 {
@@ -84,7 +84,7 @@ static bool check_type_params(pass_opt_t* opt, ast_t** astp)
     return false;
 
   ast_t* typeparams = ast_childidx(type, 1);
-  assert(ast_id(type) == TK_FUNTYPE);
+  pony_assert(ast_id(type) == TK_FUNTYPE);
 
   if(ast_id(typeparams) == TK_NONE)
     return true;
@@ -302,7 +302,7 @@ static bool auto_recover_call(ast_t* ast, ast_t* receiver_type,
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       break;
   }
 
@@ -390,7 +390,7 @@ static bool check_receiver_cap(pass_opt_t* opt, ast_t* ast, bool* recovered)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
   }
 
   if(can_recover && cap_recover)
@@ -655,7 +655,7 @@ static bool partial_application(pass_opt_t* opt, ast_t** astp)
 
   // LHS must be an application, possibly wrapped in another application
   // if the method had type parameters for qualification.
-  assert(ast_id(lhs) == TK_FUNAPP || ast_id(lhs) == TK_BEAPP ||
+  pony_assert(ast_id(lhs) == TK_FUNAPP || ast_id(lhs) == TK_BEAPP ||
     ast_id(lhs) == TK_NEWAPP);
   AST_GET_CHILDREN(lhs, receiver, method);
   ast_t* type_args = NULL;
@@ -668,12 +668,12 @@ static bool partial_application(pass_opt_t* opt, ast_t** astp)
 
   // Look up the original method definition for this method call.
   ast_t* method_def = lookup(opt, lhs, ast_type(receiver), ast_name(method));
-  assert(ast_id(method_def) == TK_FUN || ast_id(method_def) == TK_BE ||
+  pony_assert(ast_id(method_def) == TK_FUN || ast_id(method_def) == TK_BE ||
     ast_id(method_def) == TK_NEW);
 
   // The TK_FUNTYPE of the LHS.
   ast_t* type = ast_type(lhs);
-  assert(ast_id(type) == TK_FUNTYPE);
+  pony_assert(ast_id(type) == TK_FUNTYPE);
 
   if(is_typecheck_error(type))
     return false;
@@ -702,7 +702,7 @@ static bool partial_application(pass_opt_t* opt, ast_t** astp)
 
   while(given_arg != NULL)
   {
-    assert(target_param != NULL);
+    pony_assert(target_param != NULL);
     const char* target_p_name = ast_name(ast_child(target_param));
 
     if(ast_id(given_arg) == TK_NONE)
@@ -760,7 +760,7 @@ static bool partial_application(pass_opt_t* opt, ast_t** astp)
     target_param = ast_sibling(target_param);
   }
 
-  assert(target_param == NULL);
+  pony_assert(target_param == NULL);
 
   // Build lambda expression.
   // `$0.f`
diff --git a/src/libponyc/expr/control.c b/src/libponyc/expr/control.c
index 258468c59e9..819db83769e 100644
--- a/src/libponyc/expr/control.c
+++ b/src/libponyc/expr/control.c
@@ -10,7 +10,7 @@
 #include "../type/assemble.h"
 #include "../type/subtype.h"
 #include "../type/alias.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 bool expr_seq(pass_opt_t* opt, ast_t* ast)
 {
@@ -80,7 +80,7 @@ bool expr_seq(pass_opt_t* opt, ast_t* ast)
 // an if.
 static bool resolve_ifdef(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   // We turn the ifdef node into an if so that codegen doesn't need to know
   // about ifdefs at all.
@@ -386,7 +386,7 @@ bool expr_break(pass_opt_t* opt, ast_t* ast)
   }
 
   // break is always the last expression in a sequence
-  assert(ast_sibling(ast) == NULL);
+  pony_assert(ast_sibling(ast) == NULL);
 
   ast_settype(ast, ast_from(ast, TK_BREAK));
 
@@ -431,7 +431,7 @@ bool expr_continue(pass_opt_t* opt, ast_t* ast)
   }
 
   // continue is always the last expression in a sequence
-  assert(ast_sibling(ast) == NULL);
+  pony_assert(ast_sibling(ast) == NULL);
 
   ast_settype(ast, ast_from(ast, TK_CONTINUE));
   return true;
@@ -442,14 +442,14 @@ bool expr_return(pass_opt_t* opt, ast_t* ast)
   typecheck_t* t = &opt->check;
 
   // return is always the last expression in a sequence
-  assert(ast_sibling(ast) == NULL);
+  pony_assert(ast_sibling(ast) == NULL);
 
   ast_t* parent = ast_parent(ast);
   ast_t* current = ast;
 
   while(ast_id(parent) == TK_SEQ)
   {
-    assert(ast_childlast(parent) == current);
+    pony_assert(ast_childlast(parent) == current);
     current = parent;
     parent = ast_parent(parent);
   }
@@ -493,7 +493,7 @@ bool expr_return(pass_opt_t* opt, ast_t* ast)
       break;
 
     case TK_BE:
-      assert(is_none(body_type));
+      pony_assert(is_none(body_type));
       break;
 
     default:
@@ -532,7 +532,7 @@ bool expr_error(pass_opt_t* opt, ast_t* ast)
 {
   (void)opt;
   // error is always the last expression in a sequence
-  assert(ast_sibling(ast) == NULL);
+  pony_assert(ast_sibling(ast) == NULL);
 
   ast_settype(ast, ast_from(ast, TK_ERROR));
   return true;
@@ -542,7 +542,7 @@ bool expr_compile_error(pass_opt_t* opt, ast_t* ast)
 {
   (void)opt;
   // compile_error is always the last expression in a sequence
-  assert(ast_sibling(ast) == NULL);
+  pony_assert(ast_sibling(ast) == NULL);
 
   ast_settype(ast, ast_from(ast, TK_COMPILE_ERROR));
   return true;
diff --git a/src/libponyc/expr/ffi.c b/src/libponyc/expr/ffi.c
index c251a1e2e85..6c3ef81b113 100644
--- a/src/libponyc/expr/ffi.c
+++ b/src/libponyc/expr/ffi.c
@@ -2,12 +2,12 @@
 #include "literal.h"
 #include "../type/subtype.h"
 #include "../pkg/ifdef.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static bool void_star_param(ast_t* param_type, ast_t* arg_type)
 {
-  assert(param_type != NULL);
-  assert(arg_type != NULL);
+  pony_assert(param_type != NULL);
+  pony_assert(arg_type != NULL);
 
   if(!is_pointer(param_type))
     return false;
@@ -32,9 +32,9 @@ static bool void_star_param(ast_t* param_type, ast_t* arg_type)
 
 static bool declared_ffi(pass_opt_t* opt, ast_t* call, ast_t* decl)
 {
-  assert(call != NULL);
-  assert(decl != NULL);
-  assert(ast_id(decl) == TK_FFIDECL);
+  pony_assert(call != NULL);
+  pony_assert(decl != NULL);
+  pony_assert(ast_id(decl) == TK_FFIDECL);
 
   AST_GET_CHILDREN(call, call_name, call_ret_typeargs, args, named_args,
     call_error);
@@ -120,7 +120,7 @@ static bool declared_ffi(pass_opt_t* opt, ast_t* call, ast_t* decl)
 bool expr_ffi(pass_opt_t* opt, ast_t* ast)
 {
   AST_GET_CHILDREN(ast, name, return_typeargs, args, namedargs, question);
-  assert(name != NULL);
+  pony_assert(name != NULL);
 
   ast_t* decl;
   if(!ffi_get_decl(&opt->check, ast, &decl, opt))
diff --git a/src/libponyc/expr/lambda.c b/src/libponyc/expr/lambda.c
index 335a9e6bb5c..5729715c00f 100644
--- a/src/libponyc/expr/lambda.c
+++ b/src/libponyc/expr/lambda.c
@@ -8,7 +8,7 @@
 #include "../pass/syntax.h"
 #include "../type/alias.h"
 #include "../type/sanitise.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 
 // Process the given capture and create the AST for the corresponding field.
@@ -16,7 +16,7 @@
 // Returns NULL on error.
 static ast_t* make_capture_field(pass_opt_t* opt, ast_t* capture)
 {
-  assert(capture != NULL);
+  pony_assert(capture != NULL);
 
   AST_GET_CHILDREN(capture, id_node, type, value);
   const char* name = ast_name(id_node);
@@ -29,7 +29,7 @@ static ast_t* make_capture_field(pass_opt_t* opt, ast_t* capture)
   if(ast_id(value) == TK_NONE)
   {
     // Variable capture
-    assert(ast_id(type) == TK_NONE);
+    pony_assert(ast_id(type) == TK_NONE);
 
     ast_t* def = ast_get(capture, name, NULL);
 
@@ -87,9 +87,9 @@ static ast_t* make_capture_field(pass_opt_t* opt, ast_t* capture)
 
 bool expr_lambda(pass_opt_t* opt, ast_t** astp)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   ast_t* ast = *astp;
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   AST_GET_CHILDREN(ast, receiver_cap, name, t_params, params, captures,
     ret_type, raises, body, reference_cap);
diff --git a/src/libponyc/expr/literal.c b/src/libponyc/expr/literal.c
index 15d96e01425..3690b470cf9 100644
--- a/src/libponyc/expr/literal.c
+++ b/src/libponyc/expr/literal.c
@@ -8,8 +8,8 @@
 #include "../type/reify.h"
 #include "../ast/token.h"
 #include "../ast/stringtab.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 
 #define UIF_ERROR       -1
@@ -145,7 +145,7 @@ static bool unify(ast_t* ast, pass_opt_t* options, bool report_errors);
 
 static void chain_init_head(lit_chain_t* head)
 {
-  assert(head != NULL);
+  pony_assert(head != NULL);
 
   head->cardinality = CHAIN_CARD_BASE;
   head->formal = NULL;
@@ -159,7 +159,7 @@ static void chain_init_head(lit_chain_t* head)
 
 static void chain_clear_cache(lit_chain_t* chain)
 {
-  assert(chain != NULL);
+  pony_assert(chain != NULL);
 
   while(chain->cardinality != CHAIN_CARD_BASE)
     chain = chain->next;
@@ -175,14 +175,14 @@ static void chain_clear_cache(lit_chain_t* chain)
 static void chain_add(lit_chain_t* chain, lit_chain_t* new_link,
   size_t cardinality)
 {
-  assert(new_link != NULL);
-  assert(cardinality != CHAIN_CARD_BASE);
+  pony_assert(new_link != NULL);
+  pony_assert(cardinality != CHAIN_CARD_BASE);
 
   new_link->cardinality = cardinality;
   new_link->index = 0;
 
-  assert(chain != NULL);
-  assert(chain->next != NULL);
+  pony_assert(chain != NULL);
+  pony_assert(chain->next != NULL);
   new_link->next = chain->next;
   chain->next = new_link;
 
@@ -192,10 +192,10 @@ static void chain_add(lit_chain_t* chain, lit_chain_t* new_link,
 
 static void chain_remove(lit_chain_t* old_tail)
 {
-  assert(old_tail != NULL);
-  assert(old_tail->next != NULL);
-  assert(old_tail->next->next != NULL);
-  assert(old_tail->next->next->cardinality == CHAIN_CARD_BASE);
+  pony_assert(old_tail != NULL);
+  pony_assert(old_tail->next != NULL);
+  pony_assert(old_tail->next->next != NULL);
+  pony_assert(old_tail->next->next->cardinality == CHAIN_CARD_BASE);
 
   old_tail->next = old_tail->next->next;
   chain_clear_cache(old_tail);
@@ -207,7 +207,7 @@ static void chain_remove(lit_chain_t* old_tail)
 // any formal parameters.
 static int uifset_simple_type(pass_opt_t* opt, ast_t* type)
 {
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   int set = 0;
 
@@ -231,17 +231,17 @@ static int uifset_simple_type(pass_opt_t* opt, ast_t* type)
 static int uifset_formal_param(pass_opt_t* opt, ast_t* type_param_ref,
   lit_chain_t* chain)
 {
-  assert(type_param_ref != NULL);
-  assert(ast_id(type_param_ref) == TK_TYPEPARAMREF);
+  pony_assert(type_param_ref != NULL);
+  pony_assert(ast_id(type_param_ref) == TK_TYPEPARAMREF);
 
   ast_t* type_param = (ast_t*)ast_data(type_param_ref);
 
-  assert(type_param != NULL);
-  assert(ast_id(type_param) == TK_TYPEPARAM);
-  assert(chain != NULL);
+  pony_assert(type_param != NULL);
+  pony_assert(ast_id(type_param) == TK_TYPEPARAM);
+  pony_assert(chain != NULL);
 
   ast_t* constraint = ast_childidx(type_param, 1);
-  assert(constraint != NULL);
+  pony_assert(constraint != NULL);
 
   // If the constraint is not a subtype of (Real[A] & Number) then there are no
   // legal types in the set
@@ -299,8 +299,8 @@ static int uifset_formal_param(pass_opt_t* opt, ast_t* type_param_ref,
 // Determine the UIF types that the given non-tuple union type may be
 static int uifset_union(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
 {
-  assert(type != NULL);
-  assert(ast_id(type) == TK_UNIONTYPE);
+  pony_assert(type != NULL);
+  pony_assert(ast_id(type) == TK_UNIONTYPE);
 
   int uif_set = 0;
 
@@ -334,8 +334,8 @@ static int uifset_union(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
 // Determine the UIF types that the given non-tuple intersection type may be
 static int uifset_intersect(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
 {
-  assert(type != NULL);
-  assert(ast_id(type) == TK_ISECTTYPE);
+  pony_assert(type != NULL);
+  pony_assert(ast_id(type) == TK_ISECTTYPE);
 
   int uif_set = UIF_ALL_TYPES;
   int constraint = 0;
@@ -377,7 +377,7 @@ static int uifset_intersect(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
 // Determine the UIF types that the given type may be
 static int uifset(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
 {
-  assert(chain != NULL);
+  pony_assert(chain != NULL);
 
   if(is_typecheck_error(type))
     return UIF_NO_TYPES;
@@ -392,7 +392,7 @@ static int uifset(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
 
     case TK_ARROW:
       // Since we don't care about capabilities we can just use the rhs
-      assert(ast_id(ast_childidx(type, 1)) == TK_NOMINAL);
+      pony_assert(ast_id(ast_childidx(type, 1)) == TK_NOMINAL);
       return uifset(opt, ast_childidx(type, 1), chain);
 
     case TK_TYPEPARAMREF:
@@ -414,7 +414,7 @@ static int uifset(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
           return UIF_NO_TYPES;
 
         ast_t* type_args = ast_childidx(type, 2);
-        assert(ast_childcount(type_args) == 1);
+        pony_assert(ast_childcount(type_args) == 1);
         return uifset(opt, ast_child(type_args), chain->next);
       }
 
@@ -429,7 +429,7 @@ static int uifset(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
 
     default:
       ast_error(opt->check.errors, type, "Internal error: uif type, node %d", ast_id(type));
-      assert(0);
+      pony_assert(0);
       return UIF_ERROR;
   }
 }
@@ -439,8 +439,8 @@ static int uifset(pass_opt_t* opt, ast_t* type, lit_chain_t* chain)
 static bool uif_type(pass_opt_t* opt, ast_t* literal, ast_t* type,
   lit_chain_t* chain_head, bool report_errors)
 {
-  assert(chain_head != NULL);
-  assert(chain_head->cardinality == CHAIN_CARD_BASE);
+  pony_assert(chain_head != NULL);
+  pony_assert(chain_head->cardinality == CHAIN_CARD_BASE);
 
   chain_head->formal = NULL;
   int r = uifset(opt, type, chain_head->next);
@@ -457,14 +457,14 @@ static bool uif_type(pass_opt_t* opt, ast_t* literal, ast_t* type,
     return false;
   }
 
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   if((r & UIF_CONSTRAINED) != 0)
   {
     // Type is a formal parameter
-    assert(chain_head->formal != NULL);
-    assert(chain_head->name != NULL);
-    assert(chain_head->cached_uif_index < 0);
+    pony_assert(chain_head->formal != NULL);
+    pony_assert(chain_head->name != NULL);
+    pony_assert(chain_head->cached_uif_index < 0);
 
     BUILD(uif_type, type,
       NODE(TK_TYPEPARAMREF, DATA(chain_head->formal)
@@ -500,8 +500,8 @@ static bool uif_type_from_chain(pass_opt_t* opt, ast_t* literal,
   ast_t* target_type, lit_chain_t* chain, bool require_float,
   bool report_errors)
 {
-  assert(literal != NULL);
-  assert(chain != NULL);
+  pony_assert(literal != NULL);
+  pony_assert(chain != NULL);
 
   lit_chain_t* chain_head = chain;
   while(chain_head->cardinality != CHAIN_CARD_BASE)
@@ -546,7 +546,7 @@ static bool uif_type_from_chain(pass_opt_t* opt, ast_t* literal,
         // looser test if the literal is immediately negated.
         // We do not do this if the negation is not immediate, eg "-(128)".
         ast_t* parent = ast_parent(literal);
-        assert(parent != NULL);
+        pony_assert(parent != NULL);
         ast_t* parent_type = ast_type(parent);
 
         if(parent_type != NULL && ast_id(parent_type) == TK_OPERATORLITERAL &&
@@ -577,12 +577,12 @@ static bool uif_type_from_chain(pass_opt_t* opt, ast_t* literal,
 static bool coerce_group(ast_t** astp, ast_t* target_type, lit_chain_t* chain,
   size_t cardinality, pass_opt_t* options, bool report_errors)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   ast_t* literal_expr = *astp;
-  assert(literal_expr != NULL);
-  assert(ast_id(literal_expr) == TK_TUPLE || ast_id(literal_expr) == TK_ARRAY);
-  assert(chain != NULL);
-  assert(cardinality != CHAIN_CARD_BASE);
+  pony_assert(literal_expr != NULL);
+  pony_assert(ast_id(literal_expr) == TK_TUPLE || ast_id(literal_expr) == TK_ARRAY);
+  pony_assert(chain != NULL);
+  pony_assert(cardinality != CHAIN_CARD_BASE);
 
   size_t i = 0;
   lit_chain_t link;
@@ -631,20 +631,20 @@ static bool coerce_group(ast_t** astp, ast_t* target_type, lit_chain_t* chain,
 static bool coerce_control_block(ast_t** astp, ast_t* target_type,
   lit_chain_t* chain, pass_opt_t* opt, bool report_errors)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   ast_t* literal_expr = *astp;
-  assert(literal_expr != NULL);
+  pony_assert(literal_expr != NULL);
 
   ast_t* lit_type = ast_type(literal_expr);
-  assert(lit_type != NULL);
-  assert(ast_id(lit_type) == TK_LITERAL);
+  pony_assert(lit_type != NULL);
+  pony_assert(ast_id(lit_type) == TK_LITERAL);
   ast_t* block_type = ast_type(lit_type);
 
   for(ast_t* p = ast_child(lit_type); p != NULL; p = ast_sibling(p))
   {
-    assert(ast_id(p) == TK_LITERALBRANCH);
+    pony_assert(ast_id(p) == TK_LITERALBRANCH);
     ast_t* branch = (ast_t*)ast_data(p);
-    assert(branch != NULL);
+    pony_assert(branch != NULL);
 
     if(!coerce_literal_to_type(&branch, target_type, chain, opt,
       report_errors))
@@ -675,9 +675,9 @@ static bool coerce_control_block(ast_t** astp, ast_t* target_type,
 static bool coerce_literal_to_type(ast_t** astp, ast_t* target_type,
   lit_chain_t* chain, pass_opt_t* opt, bool report_errors)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   ast_t* literal_expr = *astp;
-  assert(literal_expr != NULL);
+  pony_assert(literal_expr != NULL);
 
   ast_t* lit_type = ast_type(literal_expr);
 
@@ -776,7 +776,7 @@ static bool coerce_literal_to_type(ast_t** astp, ast_t* target_type,
     default:
       ast_error(opt->check.errors, literal_expr, "Internal error, coerce_literal_to_type node %s",
         ast_get_print(literal_expr));
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -789,9 +789,9 @@ static bool coerce_literal_to_type(ast_t** astp, ast_t* target_type,
 
 bool coerce_literals(ast_t** astp, ast_t* target_type, pass_opt_t* opt)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   ast_t* literal_expr = *astp;
-  assert(literal_expr != NULL);
+  pony_assert(literal_expr != NULL);
 
   if(ast_id(literal_expr) == TK_NONE)
     return true;
@@ -814,7 +814,7 @@ bool coerce_literals(ast_t** astp, ast_t* target_type, pass_opt_t* opt)
 // Unify all the branches of the given AST to the same type
 static bool unify(ast_t* ast, pass_opt_t* opt, bool report_errors)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   ast_t* type = ast_type(ast);
 
   if(is_typecheck_error(type))
@@ -823,7 +823,7 @@ static bool unify(ast_t* ast, pass_opt_t* opt, bool report_errors)
   if(!is_type_literal(type)) // Not literal, nothing to unify
     return true;
 
-  assert(type != NULL);
+  pony_assert(type != NULL);
   ast_t* non_literal = ast_type(type);
 
   if(non_literal != NULL)
@@ -843,8 +843,8 @@ static bool unify(ast_t* ast, pass_opt_t* opt, bool report_errors)
 
 bool literal_member_access(ast_t* ast, pass_opt_t* opt)
 {
-  assert(ast != NULL);
-  assert(ast_id(ast) == TK_DOT || ast_id(ast) == TK_TILDE ||
+  pony_assert(ast != NULL);
+  pony_assert(ast_id(ast) == TK_DOT || ast_id(ast) == TK_TILDE ||
     ast_id(ast) == TK_CHAIN);
 
   AST_GET_CHILDREN(ast, receiver, name_node);
@@ -862,7 +862,7 @@ bool literal_member_access(ast_t* ast, pass_opt_t* opt)
 
   // Receiver is a pure literal expression
   // Look up member name
-  assert(ast_id(name_node) == TK_ID);
+  pony_assert(ast_id(name_node) == TK_ID);
   const char* name = ast_name(name_node);
   lit_op_info_t* op = lookup_literal_op(name);
 
@@ -882,8 +882,8 @@ bool literal_member_access(ast_t* ast, pass_opt_t* opt)
 
 bool literal_call(ast_t* ast, pass_opt_t* opt)
 {
-  assert(ast != NULL);
-  assert(ast_id(ast) == TK_CALL);
+  pony_assert(ast != NULL);
+  pony_assert(ast_id(ast) == TK_CALL);
 
   AST_GET_CHILDREN(ast, positional_args, named_args, receiver);
 
@@ -902,7 +902,7 @@ bool literal_call(ast_t* ast, pass_opt_t* opt)
     return true;
 
   lit_op_info_t* op = (lit_op_info_t*)ast_data(recv_type);
-  assert(op != NULL);
+  pony_assert(op != NULL);
 
   if(ast_childcount(named_args) != 0)
   {
@@ -947,8 +947,8 @@ bool literal_call(ast_t* ast, pass_opt_t* opt)
 
 bool literal_is(ast_t* ast, pass_opt_t* opt)
 {
-  assert(ast != NULL);
-  assert(ast_id(ast) == TK_IS || ast_id(ast) == TK_ISNT);
+  pony_assert(ast != NULL);
+  pony_assert(ast_id(ast) == TK_IS || ast_id(ast) == TK_ISNT);
 
   AST_GET_CHILDREN(ast, left, right);
 
@@ -975,8 +975,8 @@ bool literal_is(ast_t* ast, pass_opt_t* opt)
   }
 
   // Both sides are literals, that's a problem.
-  assert(is_type_literal(l_type));
-  assert(is_type_literal(r_type));
+  pony_assert(is_type_literal(l_type));
+  pony_assert(is_type_literal(r_type));
   ast_error(opt->check.errors, ast, "Cannot infer type of operands");
   return false;
 }
diff --git a/src/libponyc/expr/match.c b/src/libponyc/expr/match.c
index 994e304bf62..41ed3fbad84 100644
--- a/src/libponyc/expr/match.c
+++ b/src/libponyc/expr/match.c
@@ -9,11 +9,11 @@
 #include "../ast/id.h"
 #include "../pass/expr.h"
 #include "../pass/pass.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 bool expr_match(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_MATCH);
+  pony_assert(ast_id(ast) == TK_MATCH);
   AST_GET_CHILDREN(ast, expr, cases, else_clause);
 
   // A literal match expression should have been caught by the cases, but check
@@ -75,7 +75,7 @@ bool expr_match(pass_opt_t* opt, ast_t* ast)
 
 bool expr_cases(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_CASES);
+  pony_assert(ast_id(ast) == TK_CASES);
   ast_t* the_case = ast_child(ast);
 
   if(the_case == NULL)
@@ -268,8 +268,8 @@ static ast_t* make_pattern_type(pass_opt_t* opt, ast_t* pattern)
 static bool infer_pattern_type(ast_t* pattern, ast_t* match_expr_type,
   pass_opt_t* opt)
 {
-  assert(pattern != NULL);
-  assert(match_expr_type != NULL);
+  pony_assert(pattern != NULL);
+  pony_assert(match_expr_type != NULL);
 
   if(is_type_literal(match_expr_type))
   {
@@ -283,8 +283,8 @@ static bool infer_pattern_type(ast_t* pattern, ast_t* match_expr_type,
 
 bool expr_case(pass_opt_t* opt, ast_t* ast)
 {
-  assert(opt != NULL);
-  assert(ast_id(ast) == TK_CASE);
+  pony_assert(opt != NULL);
+  pony_assert(ast_id(ast) == TK_CASE);
   AST_GET_CHILDREN(ast, pattern, guard, body);
 
   if((ast_id(pattern) == TK_NONE) && (ast_id(guard) == TK_NONE))
@@ -379,14 +379,14 @@ bool expr_case(pass_opt_t* opt, ast_t* ast)
 bool expr_match_capture(pass_opt_t* opt, ast_t* ast)
 {
   (void)opt;
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   AST_GET_CHILDREN(ast, id, type);
 
   if(is_name_dontcare(ast_name(id)))
     ast_setid(ast, TK_MATCH_DONTCARE);
 
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   // Capture type is as specified.
   ast_settype(ast, type);
diff --git a/src/libponyc/expr/operator.c b/src/libponyc/expr/operator.c
index f8cb1c79670..5587cee5eec 100644
--- a/src/libponyc/expr/operator.c
+++ b/src/libponyc/expr/operator.c
@@ -10,11 +10,11 @@
 #include "../type/matchtype.h"
 #include "../type/safeto.h"
 #include "../type/subtype.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static bool assign_id(pass_opt_t* opt, ast_t* ast, bool let, bool need_value)
 {
-  assert(ast_id(ast) == TK_ID);
+  pony_assert(ast_id(ast) == TK_ID);
   const char* name = ast_name(ast);
 
   sym_status_t status;
@@ -77,7 +77,7 @@ static bool assign_id(pass_opt_t* opt, ast_t* ast, bool let, bool need_value)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -220,7 +220,7 @@ typedef enum infer_ret_t
 
 static ast_t* find_infer_type(pass_opt_t* opt, ast_t* type, infer_path_t* path)
 {
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   switch(ast_id(type))
   {
@@ -289,10 +289,10 @@ static ast_t* find_infer_type(pass_opt_t* opt, ast_t* type, infer_path_t* path)
 static infer_ret_t infer_local_inner(pass_opt_t* opt, ast_t* left,
   ast_t* r_type, infer_path_t* path)
 {
-  assert(left != NULL);
-  assert(r_type != NULL);
-  assert(path != NULL);
-  assert(path->root != NULL);
+  pony_assert(left != NULL);
+  pony_assert(r_type != NULL);
+  pony_assert(path != NULL);
+  pony_assert(path->root != NULL);
 
   infer_ret_t ret_val = INFER_NOP;
 
@@ -300,7 +300,7 @@ static infer_ret_t infer_local_inner(pass_opt_t* opt, ast_t* left,
   {
     case TK_SEQ:
     {
-      assert(ast_childcount(left) == 1);
+      pony_assert(ast_childcount(left) == 1);
       infer_ret_t r = infer_local_inner(opt, ast_child(left), r_type, path);
 
       if(r == INFER_OK) // Update seq type
@@ -342,7 +342,7 @@ static infer_ret_t infer_local_inner(pass_opt_t* opt, ast_t* left,
     case TK_LET:
     {
       ast_t* var_type = ast_type(left);
-      assert(var_type != NULL);
+      pony_assert(var_type != NULL);
 
       if(ast_id(var_type) != TK_INFERTYPE)  // No inferring needed
         return INFER_NOP;
@@ -364,7 +364,7 @@ static infer_ret_t infer_local_inner(pass_opt_t* opt, ast_t* left,
       // Add the type to the var / let AST as if it had been specified by the
       // user. Not really needed, but makes testing easier
       ast_t* speced_type = ast_childidx(left, 1);
-      assert(ast_id(speced_type) == TK_NONE);
+      pony_assert(ast_id(speced_type) == TK_NONE);
       ast_replace(&speced_type, a_type);
 
       ast_free_unattached(infer_type);
@@ -385,14 +385,14 @@ static bool infer_locals(pass_opt_t* opt, ast_t* left, ast_t* r_type)
   if(infer_local_inner(opt, left, r_type, &path_root) == INFER_ERROR)
     return false;
 
-  assert(path_root.next == NULL);
-  assert(path_root.root = &path_root);
+  pony_assert(path_root.next == NULL);
+  pony_assert(path_root.root = &path_root);
   return true;
 }
 
 static bool is_expr_constructor(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   switch(ast_id(ast))
   {
     case TK_CALL:
@@ -436,11 +436,11 @@ static bool is_expr_constructor(ast_t* ast)
 
 static bool tuple_contains_embed(ast_t* ast)
 {
-  assert(ast_id(ast) == TK_TUPLE);
+  pony_assert(ast_id(ast) == TK_TUPLE);
   ast_t* child = ast_child(ast);
   while(child != NULL)
   {
-    assert(ast_id(child) == TK_SEQ);
+    pony_assert(ast_id(child) == TK_SEQ);
     ast_t* member = ast_childlast(child);
     if(ast_id(member) == TK_EMBEDREF)
     {
@@ -474,7 +474,7 @@ static bool check_embed_construction(pass_opt_t* opt, ast_t* left, ast_t* right)
       ast_t* r_child = ast_child(right);
       while(l_child != NULL)
       {
-        assert((ast_id(l_child) == TK_SEQ) && (ast_id(r_child) == TK_SEQ));
+        pony_assert((ast_id(l_child) == TK_SEQ) && (ast_id(r_child) == TK_SEQ));
         ast_t* l_member = ast_childlast(l_child);
         ast_t* r_member = ast_childlast(r_child);
         if(!check_embed_construction(opt, l_member, r_member))
@@ -483,7 +483,7 @@ static bool check_embed_construction(pass_opt_t* opt, ast_t* left, ast_t* right)
         l_child = ast_sibling(l_child);
         r_child = ast_sibling(r_child);
       }
-      assert(r_child == NULL);
+      pony_assert(r_child == NULL);
     } else if(tuple_contains_embed(left)) {
       ast_error(opt->check.errors, left,
         "an embedded field must be assigned using a constructor");
@@ -498,7 +498,7 @@ bool expr_assign(pass_opt_t* opt, ast_t* ast)
 {
   // Left and right are swapped in the AST to make sure we type check the
   // right side before the left. Fetch them in the opposite order.
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   AST_GET_CHILDREN(ast, right, left);
   ast_t* l_type = ast_type(left);
@@ -583,7 +583,7 @@ bool expr_assign(pass_opt_t* opt, ast_t* ast)
         break;
 
       default:
-        assert(0);
+        pony_assert(0);
         break;
     }
 
@@ -604,7 +604,7 @@ bool expr_assign(pass_opt_t* opt, ast_t* ast)
       if(fn != NULL)
       {
         ast_t* iso = ast_child(fn);
-        assert(iso != NULL);
+        pony_assert(iso != NULL);
         token_id iso_id = ast_id(iso);
 
         if(iso_id == TK_BOX || iso_id == TK_VAL || iso_id == TK_TAG)
diff --git a/src/libponyc/expr/postfix.c b/src/libponyc/expr/postfix.c
index 114a6eab84b..7fdb56ae020 100644
--- a/src/libponyc/expr/postfix.c
+++ b/src/libponyc/expr/postfix.c
@@ -10,9 +10,9 @@
 #include "../type/reify.h"
 #include "../type/assemble.h"
 #include "../type/lookup.h"
+#include "ponyassert.h"
 #include <string.h>
 #include <stdlib.h>
-#include <assert.h>
 
 static bool is_method_called(pass_opt_t* opt, ast_t* ast)
 {
@@ -75,7 +75,7 @@ static bool constructor_type(pass_opt_t* opt, ast_t* ast, token_id cap,
           return false;
 
         default:
-          assert(0);
+          pony_assert(0);
           return false;
       }
       return true;
@@ -121,7 +121,7 @@ static bool constructor_type(pass_opt_t* opt, ast_t* ast, token_id cap,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -154,7 +154,7 @@ static bool method_access(pass_opt_t* opt, ast_t* ast, ast_t* method)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -171,8 +171,8 @@ static bool package_access(pass_opt_t* opt, ast_t** astp)
   ast_t* left = ast_child(ast);
   ast_t* right = ast_sibling(left);
 
-  assert(ast_id(left) == TK_PACKAGEREF);
-  assert(ast_id(right) == TK_ID);
+  pony_assert(ast_id(left) == TK_PACKAGEREF);
+  pony_assert(ast_id(right) == TK_ID);
 
   // Must be a type in a package.
   const char* package_name = ast_name(ast_child(left));
@@ -185,7 +185,7 @@ static bool package_access(pass_opt_t* opt, ast_t** astp)
     return false;
   }
 
-  assert(ast_id(package) == TK_PACKAGE);
+  pony_assert(ast_id(package) == TK_PACKAGE);
   const char* type_name = ast_name(right);
   ast_t* type = ast_get(package, type_name, NULL);
 
@@ -214,8 +214,8 @@ static bool type_access(pass_opt_t* opt, ast_t** astp)
   if(is_typecheck_error(type))
     return false;
 
-  assert(ast_id(left) == TK_TYPEREF);
-  assert(ast_id(right) == TK_ID);
+  pony_assert(ast_id(left) == TK_TYPEREF);
+  pony_assert(ast_id(right) == TK_ID);
 
   ast_t* find = lookup(opt, ast, type, ast_name(right));
 
@@ -273,7 +273,7 @@ static bool type_access(pass_opt_t* opt, ast_t** astp)
     }
 
     default:
-      assert(0);
+      pony_assert(0);
       ret = false;
       break;
   }
@@ -340,7 +340,7 @@ static bool tuple_access(pass_opt_t* opt, ast_t* ast)
   }
 
   type = ast_childidx(type, right_idx);
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   ast_setid(ast, TK_FLETREF);
   ast_settype(ast, type);
@@ -351,7 +351,7 @@ static bool member_access(pass_opt_t* opt, ast_t* ast)
 {
   // Left is a postfix expression, right is an id.
   AST_GET_CHILDREN(ast, left, right);
-  assert(ast_id(right) == TK_ID);
+  pony_assert(ast_id(right) == TK_ID);
   ast_t* type = ast_type(left);
 
   if(is_typecheck_error(type))
@@ -394,7 +394,7 @@ static bool member_access(pass_opt_t* opt, ast_t* ast)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       ret = false;
       break;
   }
@@ -410,7 +410,7 @@ bool expr_qualify(pass_opt_t* opt, ast_t** astp)
   ast_t* ast = *astp;
   AST_GET_CHILDREN(ast, left, right);
   ast_t* type = ast_type(left);
-  assert(ast_id(right) == TK_TYPEARGS);
+  pony_assert(ast_id(right) == TK_TYPEARGS);
 
   if(is_typecheck_error(type))
     return false;
@@ -420,7 +420,7 @@ bool expr_qualify(pass_opt_t* opt, ast_t** astp)
     case TK_TYPEREF:
     {
       // Qualify the type.
-      assert(ast_id(type) == TK_NOMINAL);
+      pony_assert(ast_id(type) == TK_NOMINAL);
 
       // If the type isn't polymorphic or the type is already qualified,
       // sugar .apply().
@@ -456,7 +456,7 @@ bool expr_qualify(pass_opt_t* opt, ast_t** astp)
     case TK_FUNCHAIN:
     {
       // Qualify the function.
-      assert(ast_id(type) == TK_FUNTYPE);
+      pony_assert(ast_id(type) == TK_FUNTYPE);
       ast_t* typeparams = ast_childidx(type, 1);
 
       if(!reify_defaults(typeparams, right, true, opt))
@@ -520,7 +520,7 @@ static bool entity_access(pass_opt_t* opt, ast_t** astp)
     return true;
 
   type = ast_type(left); // Literal handling may have changed lhs type
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   if(ast_id(type) == TK_TUPLETYPE)
     return tuple_access(opt, ast);
@@ -578,7 +578,7 @@ bool expr_tilde(pass_opt_t* opt, ast_t** astp)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -620,6 +620,6 @@ bool expr_chain(pass_opt_t* opt, ast_t** astp)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
diff --git a/src/libponyc/expr/reference.c b/src/libponyc/expr/reference.c
index 7b9d114925c..9b5b3e94968 100644
--- a/src/libponyc/expr/reference.c
+++ b/src/libponyc/expr/reference.c
@@ -15,8 +15,8 @@
 #include "../ast/astbuild.h"
 #include "../ast/id.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 /**
  * Make sure the definition of something occurs before its use. This is for
@@ -128,7 +128,7 @@ static bool valid_reference(pass_opt_t* opt, ast_t* ast, ast_t* type,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -161,7 +161,7 @@ static bool check_provides(pass_opt_t* opt, ast_t* type, ast_t* provides,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -325,7 +325,7 @@ bool expr_fieldref(pass_opt_t* opt, ast_t* ast, ast_t* find, token_id tid)
 bool expr_typeref(pass_opt_t* opt, ast_t** astp)
 {
   ast_t* ast = *astp;
-  assert(ast_id(ast) == TK_TYPEREF);
+  pony_assert(ast_id(ast) == TK_TYPEREF);
   ast_t* type = ast_type(ast);
 
   if(is_typecheck_error(type))
@@ -382,7 +382,7 @@ bool expr_typeref(pass_opt_t* opt, ast_t** astp)
         if(is_typecheck_error(type))
           return false;
 
-        assert(ast_id(type) == TK_FUNTYPE);
+        pony_assert(ast_id(type) == TK_FUNTYPE);
         AST_GET_CHILDREN(type, cap, typeparams, params, result);
 
         if(ast_id(params) == TK_NONE)
@@ -466,8 +466,8 @@ bool expr_typeref(pass_opt_t* opt, ast_t** astp)
 
 static const char* suggest_alt_name(ast_t* ast, const char* name)
 {
-  assert(ast != NULL);
-  assert(name != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(name != NULL);
 
   size_t name_len = strlen(name);
 
@@ -500,7 +500,7 @@ static const char* suggest_alt_name(ast_t* ast, const char* name)
     if(ast_id(id) != TK_ID)
       id = ast_child(id);
 
-    assert(ast_id(id) == TK_ID);
+    pony_assert(ast_id(id) == TK_ID);
     const char* try_name = ast_name(id);
 
     if(ast_get(ast, try_name, NULL) != NULL)
@@ -768,7 +768,7 @@ bool expr_reference(pass_opt_t* opt, ast_t** astp)
           break;
 
         default:
-          assert(0);
+          pony_assert(0);
           return false;
       }
 
@@ -820,17 +820,17 @@ bool expr_reference(pass_opt_t* opt, ast_t** astp)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
 bool expr_local(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
-  assert(ast_type(ast) != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(ast_type(ast) != NULL);
 
   AST_GET_CHILDREN(ast, id, type);
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   bool is_dontcare = is_name_dontcare(ast_name(id));
 
@@ -993,7 +993,7 @@ bool expr_this(pass_opt_t* opt, ast_t* ast)
     return false;
   }
 
-  assert(status == SYM_NONE);
+  pony_assert(status == SYM_NONE);
   token_id cap = cap_for_this(t);
 
   if(!cap_sendable(cap) && (t->frame->recover != NULL))
@@ -1061,7 +1061,7 @@ bool expr_this(pass_opt_t* opt, ast_t* ast)
   if((ast_id(parent) == TK_DOT) && (ast_child(parent) == ast))
   {
     ast_t* right = ast_sibling(ast);
-    assert(ast_id(right) == TK_ID);
+    pony_assert(ast_id(right) == TK_ID);
     ast_t* find = lookup_try(opt, ast, nominal, ast_name(right));
 
     if(find != NULL)
@@ -1177,7 +1177,7 @@ bool expr_nominal(pass_opt_t* opt, ast_t** astp)
   if(is_maybe(ast))
   {
     // MaybePointer[A] must be bound to a struct.
-    assert(ast_childcount(typeargs) == 1);
+    pony_assert(ast_childcount(typeargs) == 1);
     ast_t* typeparam = ast_child(typeparams);
     ast_t* typearg = ast_child(typeargs);
     bool ok = false;
@@ -1219,7 +1219,7 @@ bool expr_nominal(pass_opt_t* opt, ast_t** astp)
 
 static bool check_fields_defined(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_NEW);
+  pony_assert(ast_id(ast) == TK_NEW);
 
   ast_t* members = ast_parent(ast);
   ast_t* member = ast_child(members);
diff --git a/src/libponyc/pass/casemethod.c b/src/libponyc/pass/casemethod.c
index bdca80a1afa..42ec327bf1c 100644
--- a/src/libponyc/pass/casemethod.c
+++ b/src/libponyc/pass/casemethod.c
@@ -4,7 +4,7 @@
 #include "../ast/id.h"
 #include "../pkg/package.h"
 #include "../../libponyrt/mem/pool.h"
-#include <assert.h>
+#include "ponyassert.h"
 #include <string.h>
 
 /* The following sugar handles case methods.
@@ -55,7 +55,7 @@ class C
 // Returns: created method, NULL on error.
 static ast_t* make_match_wrapper(ast_t* case_method, pass_opt_t* opt)
 {
-  assert(case_method != NULL);
+  pony_assert(case_method != NULL);
 
   if(ast_id(case_method) == TK_FUN)
     fun_defaults(case_method);
@@ -143,12 +143,12 @@ static ast_t* make_match_wrapper(ast_t* case_method, pass_opt_t* opt)
 static bool param_with_type(ast_t* case_param, ast_t* match_param,
   ast_t* pattern, pass_opt_t* opt)
 {
-  assert(case_param != NULL);
-  assert(match_param != NULL);
-  assert(pattern != NULL);
+  pony_assert(case_param != NULL);
+  pony_assert(match_param != NULL);
+  pony_assert(pattern != NULL);
 
   AST_GET_CHILDREN(case_param, case_id, case_type, case_def_arg);
-  assert(ast_id(case_type) != TK_NONE);
+  pony_assert(ast_id(case_type) != TK_NONE);
 
   if(ast_id(case_id) != TK_ID)
   {
@@ -159,7 +159,7 @@ static bool param_with_type(ast_t* case_param, ast_t* match_param,
   }
 
   AST_GET_CHILDREN(match_param, match_id, match_type, match_def_arg);
-  assert(ast_id(match_id) == TK_ID || ast_id(match_id) == TK_NONE);
+  pony_assert(ast_id(match_id) == TK_ID || ast_id(match_id) == TK_NONE);
 
   if(ast_id(match_id) == TK_NONE)
   {
@@ -220,11 +220,11 @@ static bool param_with_type(ast_t* case_param, ast_t* match_param,
 static bool param_without_type(ast_t* case_param, ast_t* pattern,
   pass_opt_t* opt)
 {
-  assert(case_param != NULL);
-  assert(pattern != NULL);
+  pony_assert(case_param != NULL);
+  pony_assert(pattern != NULL);
 
   AST_GET_CHILDREN(case_param, value, type, def_arg);
-  assert(ast_id(type) == TK_NONE);
+  pony_assert(ast_id(type) == TK_NONE);
 
   if(ast_id(def_arg) != TK_NONE)
   {
@@ -251,8 +251,8 @@ static bool param_without_type(ast_t* case_param, ast_t* pattern,
 static ast_t* process_params(ast_t* match_params, ast_t* case_params,
   pass_opt_t* opt)
 {
-  assert(match_params != NULL);
-  assert(case_params != NULL);
+  pony_assert(match_params != NULL);
+  pony_assert(case_params != NULL);
 
   bool ok = true;
   size_t count = 0;
@@ -297,7 +297,7 @@ static ast_t* process_params(ast_t* match_params, ast_t* case_params,
     return NULL;
   }
 
-  assert(count > 0);
+  pony_assert(count > 0);
   if(count == 1)
   {
     // Only one parameter, don't need a tuple pattern.
@@ -317,14 +317,14 @@ static ast_t* process_params(ast_t* match_params, ast_t* case_params,
 static ast_t* build_params(ast_t* match_params, ast_t* worker_params,
   ast_t* call_args, const char* name, pass_opt_t* opt)
 {
-  assert(match_params != NULL);
-  assert(worker_params != NULL);
-  assert(call_args != NULL);
-  assert(name != NULL);
-  assert(opt != NULL);
+  pony_assert(match_params != NULL);
+  pony_assert(worker_params != NULL);
+  pony_assert(call_args != NULL);
+  pony_assert(name != NULL);
+  pony_assert(opt != NULL);
 
   typecheck_t* t = &opt->check;
-  assert(t != NULL);
+  pony_assert(t != NULL);
 
   ast_t* match_operand = ast_from(match_params, TK_TUPLE);
   size_t count = 0;
@@ -337,7 +337,7 @@ static ast_t* build_params(ast_t* match_params, ast_t* worker_params,
 
     if(ast_id(id) == TK_NONE)
     {
-      assert(ast_id(type) == TK_NONE);
+      pony_assert(ast_id(type) == TK_NONE);
       ast_error(opt->check.errors, p,
         "name and type not specified for parameter " __zu
         " of case function %s",
@@ -383,7 +383,7 @@ static ast_t* build_params(ast_t* match_params, ast_t* worker_params,
     return NULL;
   }
 
-  assert(count > 0);
+  pony_assert(count > 0);
   if(count == 1)
   {
     // Only one parameter, don't need tuple in operand.
@@ -403,14 +403,14 @@ static ast_t* build_params(ast_t* match_params, ast_t* worker_params,
 static bool process_t_param(ast_t* case_param, ast_t* match_param,
   pass_opt_t* opt)
 {
-  assert(case_param != NULL);
-  assert(match_param != NULL);
+  pony_assert(case_param != NULL);
+  pony_assert(match_param != NULL);
 
   AST_GET_CHILDREN(case_param, case_id, case_constraint, case_def_type);
-  assert(ast_id(case_id) == TK_ID);
+  pony_assert(ast_id(case_id) == TK_ID);
 
   AST_GET_CHILDREN(match_param, match_id, match_constraint, match_def_type);
-  assert(ast_id(match_id) == TK_ID || ast_id(match_id) == TK_NONE);
+  pony_assert(ast_id(match_id) == TK_ID || ast_id(match_id) == TK_NONE);
 
   if(ast_id(match_id) == TK_NONE)
   {
@@ -476,8 +476,8 @@ static bool process_t_param(ast_t* case_param, ast_t* match_param,
 static bool process_t_params(ast_t* match_params, ast_t* case_params,
   pass_opt_t* opt)
 {
-  assert(match_params != NULL);
-  assert(case_params != NULL);
+  pony_assert(match_params != NULL);
+  pony_assert(case_params != NULL);
 
   bool ok = true;
   ast_t* case_param = ast_child(case_params);
@@ -511,13 +511,13 @@ static bool process_t_params(ast_t* match_params, ast_t* case_params,
 static void build_t_params(ast_t* match_t_params,
   ast_t* worker_t_params)
 {
-  assert(match_t_params != NULL);
-  assert(worker_t_params != NULL);
+  pony_assert(match_t_params != NULL);
+  pony_assert(worker_t_params != NULL);
 
   for(ast_t* p = ast_child(match_t_params); p != NULL; p = ast_sibling(p))
   {
     AST_GET_CHILDREN(p, id, constraint, def_type);
-    assert(ast_id(id) == TK_ID);
+    pony_assert(ast_id(id) == TK_ID);
 
     // Add type parameter name to worker call list.
     BUILD(type, p, NODE(TK_NOMINAL, NONE TREE(id) NONE NONE NONE));
@@ -641,8 +641,8 @@ static void add_docstring(ast_t* id, ast_t* match_docstring,
 static ast_t* add_case_method(ast_t* match_method, ast_t* case_method,
   pass_opt_t* opt)
 {
-  assert(match_method != NULL);
-  assert(case_method != NULL);
+  pony_assert(match_method != NULL);
+  pony_assert(case_method != NULL);
 
   // We need default capabality and return value if not provided explicitly.
   if(ast_id(case_method) == TK_FUN)
@@ -740,13 +740,13 @@ static ast_t* add_case_method(ast_t* match_method, ast_t* case_method,
 static bool sugar_case_method(ast_t* first_case_method, ast_t* members,
   const char* name, pass_opt_t* opt)
 {
-  assert(first_case_method != NULL);
-  assert(members != NULL);
-  assert(name != NULL);
-  assert(opt != NULL);
+  pony_assert(first_case_method != NULL);
+  pony_assert(members != NULL);
+  pony_assert(name != NULL);
+  pony_assert(opt != NULL);
 
   typecheck_t* t = &opt->check;
-  assert(t != NULL);
+  pony_assert(t != NULL);
 
   ast_t* wrapper = make_match_wrapper(first_case_method, opt);
 
@@ -803,8 +803,8 @@ static bool sugar_case_method(ast_t* first_case_method, ast_t* members,
   ast_t* wrapper_body = ast_childidx(wrapper, 6);
   ast_t* wrapper_call;
   ast_t* call_t_args = ast_from(wrapper, TK_NONE);
-  assert(ast_id(wrapper_body) == TK_SEQ);
-  assert(ast_childcount(wrapper_body) == 0);
+  pony_assert(ast_id(wrapper_body) == TK_SEQ);
+  pony_assert(ast_childcount(wrapper_body) == 0);
 
   build_t_params(ast_childidx(wrapper, 2), call_t_args);
 
@@ -873,8 +873,8 @@ static bool sugar_case_method(ast_t* first_case_method, ast_t* members,
 // Sugar any case methods in the given entity.
 ast_result_t sugar_case_methods(pass_opt_t* opt, ast_t* entity)
 {
-  assert(opt != NULL);
-  assert(entity != NULL);
+  pony_assert(opt != NULL);
+  pony_assert(entity != NULL);
 
   ast_result_t result = AST_OK;
   ast_t* members = ast_childidx(entity, 4);
diff --git a/src/libponyc/pass/docgen.c b/src/libponyc/pass/docgen.c
index d7f091dbb4f..6c14b360a92 100644
--- a/src/libponyc/pass/docgen.c
+++ b/src/libponyc/pass/docgen.c
@@ -3,7 +3,7 @@
 #include "../ast/printbuf.h"
 #include "../pkg/package.h"
 #include "../../libponyrt/mem/pool.h"
-#include <assert.h>
+#include "ponyassert.h"
 #include <stdio.h>
 #include <string.h>
 
@@ -59,7 +59,7 @@ typedef struct ast_list_t
 // handled separately
 static void doc_list_free(ast_list_t* list)
 {
-  assert(list != NULL);
+  pony_assert(list != NULL);
 
   ast_list_t* p = list->next;
 
@@ -76,8 +76,8 @@ static void doc_list_free(ast_list_t* list)
 static void doc_list_add(ast_list_t* list, ast_t* ast, const char* name,
   bool sort)
 {
-  assert(list != NULL);
-  assert(ast != NULL);
+  pony_assert(list != NULL);
+  pony_assert(ast != NULL);
 
   ast_list_t* n = POOL_ALLOC(ast_list_t);
   n->ast = ast;
@@ -90,7 +90,7 @@ static void doc_list_add(ast_list_t* list, ast_t* ast, const char* name,
 
   for(ast_list_t* p = prev->next; p != NULL; prev = p, p = p->next)
   {
-    assert(p->name != NULL);
+    pony_assert(p->name != NULL);
 
     if (sort && strcmp(p->name, name) > 0)
     {
@@ -115,11 +115,11 @@ static void doc_list_add(ast_list_t* list, ast_t* ast, const char* name,
 static void doc_list_add_named(ast_list_t* list, ast_t* ast, size_t id_index,
   bool allow_public, bool allow_private)
 {
-  assert(list != NULL);
-  assert(ast != NULL);
+  pony_assert(list != NULL);
+  pony_assert(ast != NULL);
 
   const char* name = ast_name(ast_childidx(ast, id_index));
-  assert(name != NULL);
+  pony_assert(name != NULL);
 
   if(is_name_internal_test(name))  // Ignore internally generated names
     return;
@@ -148,12 +148,12 @@ static void doc_list_add_named(ast_list_t* list, ast_t* ast, size_t id_index,
 static char* doc_cat(const char* a, const char* b, const char* c,
   const char* d, const char* e, size_t* out_buf_size)
 {
-  assert(a != NULL);
-  assert(b != NULL);
-  assert(c != NULL);
-  assert(d != NULL);
-  assert(e != NULL);
-  assert(out_buf_size != NULL);
+  pony_assert(a != NULL);
+  pony_assert(b != NULL);
+  pony_assert(c != NULL);
+  pony_assert(d != NULL);
+  pony_assert(e != NULL);
+  pony_assert(out_buf_size != NULL);
 
   size_t a_len = strlen(a);
   size_t b_len = strlen(b);
@@ -173,7 +173,7 @@ static char* doc_cat(const char* a, const char* b, const char* c,
 
   *(p++) = '\0';
 
-  assert(p == (buffer + buf_len));
+  pony_assert(p == (buffer + buf_len));
   *out_buf_size = buf_len;
   return buffer;
 }
@@ -195,11 +195,11 @@ static char* doc_cat(const char* a, const char* b, const char* c,
 // terminator.
 static char* write_tqfn(ast_t* type, const char* type_name, size_t* out_size)
 {
-  assert(type != NULL);
-  assert(out_size != NULL);
+  pony_assert(type != NULL);
+  pony_assert(out_size != NULL);
 
   ast_t* package = ast_nearest(type, TK_PACKAGE);
-  assert(package != NULL);
+  pony_assert(package != NULL);
 
   // We need the qualified package name and the type name
   const char* pkg_qual_name = package_qualified_name(package);
@@ -207,8 +207,8 @@ static char* write_tqfn(ast_t* type, const char* type_name, size_t* out_size)
   if(type_name == NULL)
     type_name = ast_name(ast_child(type));
 
-  assert(pkg_qual_name != NULL);
-  assert(type_name != NULL);
+  pony_assert(pkg_qual_name != NULL);
+  pony_assert(type_name != NULL);
 
   char* buffer = doc_cat(pkg_qual_name, "-", type_name, "", "", out_size);
 
@@ -235,9 +235,9 @@ static char* write_tqfn(ast_t* type, const char* type_name, size_t* out_size)
 static FILE* doc_open_file(docgen_t* docgen, bool in_sub_dir,
   const char* filename, const char* extn)
 {
-  assert(docgen != NULL);
-  assert(filename != NULL);
-  assert(extn != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(filename != NULL);
+  pony_assert(extn != NULL);
 
   // Build the type file name in a buffer.
   // Full file name is:
@@ -293,9 +293,9 @@ static const char* doc_get_cap(ast_t* cap)
 // Write the given type to the current type file
 static void doc_type(docgen_t* docgen, ast_t* type, bool generate_links)
 {
-  assert(docgen != NULL);
-  assert(docgen->type_file != NULL);
-  assert(type != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->type_file != NULL);
+  pony_assert(type != NULL);
 
   switch(ast_id(type))
   {
@@ -309,7 +309,7 @@ static void doc_type(docgen_t* docgen, ast_t* type, bool generate_links)
       {
         // Find type we reference so we can link to it
         ast_t* target = (ast_t*)ast_data(type);
-        assert(target != NULL);
+        pony_assert(target != NULL);
 
         size_t link_len;
         char* tqfn = write_tqfn(target, NULL, &link_len);
@@ -386,7 +386,7 @@ static void doc_type(docgen_t* docgen, ast_t* type, bool generate_links)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
   }
 }
 
@@ -396,12 +396,12 @@ static void doc_type(docgen_t* docgen, ast_t* type, bool generate_links)
 static void doc_type_list(docgen_t* docgen, ast_t* list, const char* preamble,
   const char* separator, const char* postamble, bool generate_links, bool line_breaks)
 {
-  assert(docgen != NULL);
-  assert(docgen->type_file != NULL);
-  assert(list != NULL);
-  assert(preamble != NULL);
-  assert(separator != NULL);
-  assert(postamble != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->type_file != NULL);
+  pony_assert(list != NULL);
+  pony_assert(preamble != NULL);
+  pony_assert(separator != NULL);
+  pony_assert(postamble != NULL);
 
   if(ast_id(list) == TK_NONE)
     return;
@@ -431,8 +431,8 @@ static void doc_type_list(docgen_t* docgen, ast_t* list, const char* preamble,
 
 static bool is_for_testing(const char* name, ast_t* list)
 {
-  assert(name != NULL);
-  assert(list != NULL);
+  pony_assert(name != NULL);
+  pony_assert(list != NULL);
 
   if (strncmp(name, "_Test", 5) == 0) return true;
 
@@ -465,10 +465,10 @@ static bool is_for_testing(const char* name, ast_t* list)
 // If the field list is empty nothing is written.
 static void doc_fields(docgen_t* docgen, ast_list_t* fields, const char* title)
 {
-  assert(docgen != NULL);
-  assert(docgen->type_file != NULL);
-  assert(fields != NULL);
-  assert(title != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->type_file != NULL);
+  pony_assert(fields != NULL);
+  pony_assert(title != NULL);
 
   if(fields->next == NULL)  // No fields
     return;
@@ -478,11 +478,11 @@ static void doc_fields(docgen_t* docgen, ast_list_t* fields, const char* title)
   for(ast_list_t* p = fields->next; p != NULL; p = p->next)
   {
     ast_t* field = p->ast;
-    assert(field != NULL);
+    pony_assert(field != NULL);
 
     AST_GET_CHILDREN(field, id, type, init);
     const char* name = ast_name(id);
-    assert(name != NULL);
+    pony_assert(name != NULL);
 
     // Don't want ast_get_print() as that will give us flet or fvar
     const char* ftype = NULL;
@@ -492,7 +492,7 @@ static void doc_fields(docgen_t* docgen, ast_list_t* fields, const char* title)
       case TK_FVAR: ftype = "var"; break;
       case TK_FLET: ftype = "let"; break;
       case TK_EMBED: ftype = "embed"; break;
-      default: assert(0);
+      default: pony_assert(0);
     }
 
     fprintf(docgen->type_file, "* %s %s: ", ftype, name);
@@ -507,14 +507,14 @@ static void doc_fields(docgen_t* docgen, ast_list_t* fields, const char* title)
 static void doc_type_params(docgen_t* docgen, ast_t* t_params,
   bool generate_links)
 {
-  assert(docgen != NULL);
-  assert(docgen->type_file != NULL);
-  assert(t_params != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->type_file != NULL);
+  pony_assert(t_params != NULL);
 
   if(ast_id(t_params) == TK_NONE)
     return;
 
-  assert(ast_id(t_params) == TK_TYPEPARAMS);
+  pony_assert(ast_id(t_params) == TK_TYPEPARAMS);
 
   if(generate_links)
     fprintf(docgen->type_file, "\\[");
@@ -529,7 +529,7 @@ static void doc_type_params(docgen_t* docgen, ast_t* t_params,
 
     AST_GET_CHILDREN(t_param, id, constraint, default_type);
     const char* name = ast_name(id);
-    assert(name != NULL);
+    pony_assert(name != NULL);
 
     if(ast_id(default_type) != TK_NONE)
       fprintf(docgen->type_file, "optional ");
@@ -552,9 +552,9 @@ static void doc_type_params(docgen_t* docgen, ast_t* t_params,
 // surrounding (). If the given list is empty () is still written.
 static void code_block_doc_params(docgen_t* docgen, ast_t* params)
 {
-  assert(docgen != NULL);
-  assert(docgen->type_file != NULL);
-  assert(params != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->type_file != NULL);
+  pony_assert(params != NULL);
 
   fprintf(docgen->type_file, "(");
   ast_t* first = ast_child(params);
@@ -568,7 +568,7 @@ static void code_block_doc_params(docgen_t* docgen, ast_t* params)
 
     AST_GET_CHILDREN(param, id, type, def_val);
     const char* name = ast_name(id);
-    assert(name != NULL);
+    pony_assert(name != NULL);
 
     fprintf(docgen->type_file, "  %s: ", name);
     doc_type(docgen, type, false);
@@ -594,9 +594,9 @@ static void code_block_doc_params(docgen_t* docgen, ast_t* params)
 
 static void list_doc_params(docgen_t* docgen, ast_t* params)
 {
-  assert(docgen != NULL);
-  assert(docgen->type_file != NULL);
-  assert(params != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->type_file != NULL);
+  pony_assert(params != NULL);
 
   ast_t* first = ast_child(params);
 
@@ -609,7 +609,7 @@ static void list_doc_params(docgen_t* docgen, ast_t* params)
 
     AST_GET_CHILDREN(param, id, type, def_val);
     const char* name = ast_name(id);
-    assert(name != NULL);
+    pony_assert(name != NULL);
 
     fprintf(docgen->type_file, "  %s: ", name);
     doc_type(docgen, type, true);
@@ -638,14 +638,14 @@ static void list_doc_params(docgen_t* docgen, ast_t* params)
 // Write a description of the given method to the current type file
 static void doc_method(docgen_t* docgen, ast_t* method)
 {
-  assert(docgen != NULL);
-  assert(docgen->type_file != NULL);
-  assert(method != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->type_file != NULL);
+  pony_assert(method != NULL);
 
   AST_GET_CHILDREN(method, cap, id, t_params, params, ret, error, body, doc);
 
   const char* name = ast_name(id);
-  assert(name != NULL);
+  pony_assert(name != NULL);
 
   // Method
   fprintf(docgen->type_file, "### %s", name);
@@ -710,10 +710,10 @@ static void doc_method(docgen_t* docgen, ast_t* method)
 static void doc_methods(docgen_t* docgen, ast_list_t* methods,
   const char* variety)
 {
-  assert(docgen != NULL);
-  assert(docgen->type_file != NULL);
-  assert(methods != NULL);
-  assert(variety != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->type_file != NULL);
+  pony_assert(methods != NULL);
+  pony_assert(variety != NULL);
 
   if(methods->next == NULL)
     return;
@@ -728,14 +728,14 @@ static void doc_methods(docgen_t* docgen, ast_list_t* methods,
 // Write a description of the given entity to its own type file.
 static void doc_entity(docgen_t* docgen, ast_t* ast)
 {
-  assert(docgen != NULL);
-  assert(docgen->index_file != NULL);
-  assert(docgen->package_file != NULL);
-  assert(docgen->test_types != NULL);
-  assert(docgen->public_types != NULL);
-  assert(docgen->private_types != NULL);
-  assert(docgen->type_file == NULL);
-  assert(ast != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->index_file != NULL);
+  pony_assert(docgen->package_file != NULL);
+  pony_assert(docgen->test_types != NULL);
+  pony_assert(docgen->public_types != NULL);
+  pony_assert(docgen->private_types != NULL);
+  pony_assert(docgen->type_file == NULL);
+  pony_assert(ast != NULL);
 
   // First open a file
   size_t tqfn_len;
@@ -750,7 +750,7 @@ static void doc_entity(docgen_t* docgen, ast_t* ast)
   AST_GET_CHILDREN(ast, id, tparams, cap, provides, members, c_api, doc);
 
   const char* name = ast_name(id);
-  assert(name != NULL);
+  pony_assert(name != NULL);
 
   fprintf(docgen->index_file, "  - %s %s: \"%s.md\"\n",
     ast_get_print(ast), name, tqfn);
@@ -826,7 +826,7 @@ static void doc_entity(docgen_t* docgen, ast_t* ast)
         break;
 
       default:
-        assert(0);
+        pony_assert(0);
         break;
     }
   }
@@ -856,16 +856,16 @@ static void doc_package_home(docgen_t* docgen,
   ast_t* package,
   ast_t* doc_string)
 {
-  assert(docgen != NULL);
-  assert(docgen->index_file != NULL);
-  assert(docgen->home_file != NULL);
-  assert(docgen->package_file == NULL);
-  assert(docgen->test_types == NULL);
-  assert(docgen->public_types == NULL);
-  assert(docgen->private_types == NULL);
-  assert(docgen->type_file == NULL);
-  assert(package != NULL);
-  assert(ast_id(package) == TK_PACKAGE);
+  pony_assert(docgen != NULL);
+  pony_assert(docgen->index_file != NULL);
+  pony_assert(docgen->home_file != NULL);
+  pony_assert(docgen->package_file == NULL);
+  pony_assert(docgen->test_types == NULL);
+  pony_assert(docgen->public_types == NULL);
+  pony_assert(docgen->private_types == NULL);
+  pony_assert(docgen->type_file == NULL);
+  pony_assert(package != NULL);
+  pony_assert(ast_id(package) == TK_PACKAGE);
 
   // First open a file
   size_t tqfn_len;
@@ -890,7 +890,7 @@ static void doc_package_home(docgen_t* docgen,
   // Now we can write the actual documentation for the package
   if(doc_string != NULL)
   {
-    assert(ast_id(doc_string) == TK_STRING);
+    pony_assert(ast_id(doc_string) == TK_STRING);
     fprintf(docgen->type_file, "%s", ast_name(doc_string));
   }
   else
@@ -913,12 +913,12 @@ static void doc_package_home(docgen_t* docgen,
 // Document the given package
 static void doc_package(docgen_t* docgen, ast_t* ast)
 {
-  assert(ast != NULL);
-  assert(ast_id(ast) == TK_PACKAGE);
-  assert(docgen->package_file == NULL);
-  assert(docgen->test_types == NULL);
-  assert(docgen->public_types == NULL);
-  assert(docgen->private_types == NULL);
+  pony_assert(ast != NULL);
+  pony_assert(ast_id(ast) == TK_PACKAGE);
+  pony_assert(docgen->package_file == NULL);
+  pony_assert(docgen->test_types == NULL);
+  pony_assert(docgen->public_types == NULL);
+  pony_assert(docgen->private_types == NULL);
 
   ast_list_t types = { NULL, NULL, NULL };
   ast_t* package_doc = NULL;
@@ -929,18 +929,18 @@ static void doc_package(docgen_t* docgen, ast_t* ast)
     if(ast_id(m) == TK_STRING)
     {
       // Package docstring
-      assert(package_doc == NULL);
+      pony_assert(package_doc == NULL);
       package_doc = m;
     }
     else
     {
-      assert(ast_id(m) == TK_MODULE);
+      pony_assert(ast_id(m) == TK_MODULE);
 
       for(ast_t* t = ast_child(m); t != NULL; t = ast_sibling(t))
       {
         if(ast_id(t) != TK_USE)
         {
-          assert(ast_id(t) == TK_TYPE || ast_id(t) == TK_INTERFACE ||
+          pony_assert(ast_id(t) == TK_TYPE || ast_id(t) == TK_INTERFACE ||
             ast_id(t) == TK_TRAIT || ast_id(t) == TK_PRIMITIVE ||
             ast_id(t) == TK_STRUCT || ast_id(t) == TK_CLASS ||
             ast_id(t) == TK_ACTOR);
@@ -990,19 +990,19 @@ static void doc_package(docgen_t* docgen, ast_t* ast)
 // Document the packages in the given program
 static void doc_packages(docgen_t* docgen, ast_t* ast)
 {
-  assert(ast != NULL);
-  assert(ast_id(ast) == TK_PROGRAM);
+  pony_assert(ast != NULL);
+  pony_assert(ast_id(ast) == TK_PROGRAM);
 
   // The Main package appears first, other packages in alphabetical order
   ast_t* package_1 = ast_child(ast);
-  assert(package_1 != NULL);
+  pony_assert(package_1 != NULL);
 
   ast_list_t packages = { NULL, NULL, NULL };
 
   // Sort packages
   for(ast_t* p = ast_sibling(package_1); p != NULL; p = ast_sibling(p))
   {
-    assert(ast_id(p) == TK_PACKAGE);
+    pony_assert(ast_id(p) == TK_PACKAGE);
 
     const char* name = package_qualified_name(p);
     doc_list_add(&packages, p, name, true);
@@ -1023,7 +1023,7 @@ static void doc_packages(docgen_t* docgen, ast_t* ast)
 // Delete all the files in the specified directory
 static void doc_rm_star(const char* path)
 {
-  assert(path != NULL);
+  pony_assert(path != NULL);
 
   PONY_ERRNO err;
   PONY_DIR* dir = pony_opendir(path, &err);
@@ -1070,9 +1070,9 @@ static void doc_rm_star(const char* path)
  */
 static void doc_setup_dirs(docgen_t* docgen, ast_t* program, pass_opt_t* opt)
 {
-  assert(docgen != NULL);
-  assert(program != NULL);
-  assert(opt != NULL);
+  pony_assert(docgen != NULL);
+  pony_assert(program != NULL);
+  pony_assert(opt != NULL);
 
   // First build our directory strings
   const char* output = opt->output;
@@ -1099,7 +1099,7 @@ static void doc_setup_dirs(docgen_t* docgen, ast_t* program, pass_opt_t* opt)
 
 void generate_docs(ast_t* program, pass_opt_t* options)
 {
-  assert(program != NULL);
+  pony_assert(program != NULL);
 
   if(ast_id(program) != TK_PROGRAM)
     return;
diff --git a/src/libponyc/pass/expr.c b/src/libponyc/pass/expr.c
index 21eba283016..65e5474eb5f 100644
--- a/src/libponyc/pass/expr.c
+++ b/src/libponyc/pass/expr.c
@@ -9,7 +9,7 @@
 #include "../expr/array.h"
 #include "../expr/ffi.h"
 #include "../expr/lambda.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static bool is_numeric_primitive(const char* name)
 {
@@ -81,7 +81,7 @@ bool is_result_needed(ast_t* ast)
     {
       // Only if it is a numeric primitive constructor.
       ast_t* type = ast_childidx(parent, 4);
-      assert(ast_id(type) == TK_NOMINAL);
+      pony_assert(ast_id(type) == TK_NOMINAL);
       const char* pkg_name = ast_name(ast_child(type));
       const char* type_name = ast_name(ast_childidx(type, 1));
       if(pkg_name == stringtab("$0")) // Builtin package.
@@ -321,7 +321,7 @@ ast_result_t pass_expr(ast_t** astp, pass_opt_t* options)
 
   if(!r)
   {
-    assert(errors_get_count(options->check.errors) > 0);
+    pony_assert(errors_get_count(options->check.errors) > 0);
     return AST_ERROR;
   }
 
diff --git a/src/libponyc/pass/finalisers.c b/src/libponyc/pass/finalisers.c
index 3d0ace8ffa6..27bfd8c44dc 100644
--- a/src/libponyc/pass/finalisers.c
+++ b/src/libponyc/pass/finalisers.c
@@ -2,9 +2,9 @@
 #include "../type/lookup.h"
 #include "../type/subtype.h"
 #include "../type/reify.h"
+#include "ponyassert.h"
 #include <string.h>
 #include <stdio.h>
-#include <assert.h>
 
 enum
 {
@@ -118,11 +118,11 @@ static int check_call_send(ast_t* ast, bool in_final)
     return FINAL_CAN_SEND;
 
   ast_t* def = receiver_def(type);
-  assert(def != NULL);
+  pony_assert(def != NULL);
 
   const char* method_name = ast_name(method);
   ast_t* fun = ast_get(def, method_name, NULL);
-  assert(fun != NULL);
+  pony_assert(fun != NULL);
 
   AST_GET_CHILDREN(fun, cap, id, typeparams, params, result, can_error, body);
   int r = check_body_send(body, false);
diff --git a/src/libponyc/pass/flatten.c b/src/libponyc/pass/flatten.c
index 60a198318d8..f28effab5d8 100644
--- a/src/libponyc/pass/flatten.c
+++ b/src/libponyc/pass/flatten.c
@@ -5,7 +5,7 @@
 #include "../type/compattype.h"
 #include "../type/subtype.h"
 #include "../type/typeparam.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static ast_result_t flatten_union(pass_opt_t* opt, ast_t** astp)
 {
@@ -167,10 +167,10 @@ static ast_result_t flatten_async(pass_opt_t* opt, ast_t* ast)
 static bool flatten_provided_type(pass_opt_t* opt, ast_t* provides_type,
   ast_t* error_at, ast_t* list_parent, ast_t** list_end)
 {
-  assert(error_at != NULL);
-  assert(provides_type != NULL);
-  assert(list_parent != NULL);
-  assert(list_end != NULL);
+  pony_assert(error_at != NULL);
+  pony_assert(provides_type != NULL);
+  pony_assert(list_parent != NULL);
+  pony_assert(list_end != NULL);
 
   switch(ast_id(provides_type))
   {
@@ -189,7 +189,7 @@ static bool flatten_provided_type(pass_opt_t* opt, ast_t* provides_type,
     {
       // Check type is a trait or interface
       ast_t* def = (ast_t*)ast_data(provides_type);
-      assert(def != NULL);
+      pony_assert(def != NULL);
 
       if(ast_id(def) != TK_TRAIT && ast_id(def) != TK_INTERFACE)
       {
@@ -220,7 +220,7 @@ static bool flatten_provided_type(pass_opt_t* opt, ast_t* provides_type,
 static ast_result_t flatten_provides_list(pass_opt_t* opt, ast_t* provider,
   int index)
 {
-  assert(provider != NULL);
+  pony_assert(provider != NULL);
 
   ast_t* provides = ast_childidx(provider, index);
 
diff --git a/src/libponyc/pass/import.c b/src/libponyc/pass/import.c
index d2703ca50e7..6e6b741f5d0 100644
--- a/src/libponyc/pass/import.c
+++ b/src/libponyc/pass/import.c
@@ -2,13 +2,13 @@
 #include "../ast/ast.h"
 #include "../ast/symtab.h"
 #include "../ast/id.h"
-#include <assert.h>
+#include "ponyassert.h"
 #include <string.h>
 
 
 static bool import_use(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   ast_t* import = (ast_t*)ast_data(ast);
 
@@ -16,17 +16,17 @@ static bool import_use(pass_opt_t* opt, ast_t* ast)
     return true;
 
   ast_t* module = ast_parent(ast);
-  assert(ast_id(module) == TK_MODULE);
+  pony_assert(ast_id(module) == TK_MODULE);
   symtab_t* mod_symtab = ast_get_symtab(module);
 
   ast_t* package = ast_parent(module);
-  assert(ast_id(package) == TK_PACKAGE);
+  pony_assert(ast_id(package) == TK_PACKAGE);
   symtab_t* pkg_symtab = ast_get_symtab(package);
 
   ast_t* uri_child = ast_childidx(ast, 1);
-  assert(uri_child != NULL);
+  pony_assert(uri_child != NULL);
   const char* uri = ast_name(uri_child);
-  assert(uri != NULL);
+  pony_assert(uri != NULL);
 
   bool is_builtin = (strcmp(uri, "builtin") == 0);
   bool ok = true;
@@ -34,7 +34,7 @@ static bool import_use(pass_opt_t* opt, ast_t* ast)
   size_t i = HASHMAP_BEGIN;
   symbol_t* sym;
   symtab_t* src_symtab = ast_get_symtab(import);
-  assert(src_symtab != NULL);
+  pony_assert(src_symtab != NULL);
 
   while((sym = symtab_next(src_symtab, &i)) != NULL)
   {
diff --git a/src/libponyc/pass/names.c b/src/libponyc/pass/names.c
index 8c858afa581..9e13f0ca1c1 100644
--- a/src/libponyc/pass/names.c
+++ b/src/libponyc/pass/names.c
@@ -4,7 +4,7 @@
 #include "../type/reify.h"
 #include "../type/viewpoint.h"
 #include "../pkg/package.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static bool names_applycap(pass_opt_t* opt, ast_t* ast, ast_t* cap,
   ast_t* ephemeral)
@@ -63,7 +63,7 @@ static bool names_applycap(pass_opt_t* opt, ast_t* ast, ast_t* cap,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -91,7 +91,7 @@ static bool names_resolvealias(pass_opt_t* opt, ast_t* def, ast_t** type)
       return false;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -169,7 +169,7 @@ static bool names_typeparam(pass_opt_t* opt, ast_t** astp, ast_t* def)
 {
   ast_t* ast = *astp;
   AST_GET_CHILDREN(ast, package, id, typeargs, cap, ephemeral);
-  assert(ast_id(package) == TK_NONE);
+  pony_assert(ast_id(package) == TK_NONE);
 
   if(ast_id(typeargs) != TK_NONE)
   {
@@ -240,7 +240,7 @@ static bool names_type(pass_opt_t* opt, ast_t** astp, ast_t* def)
 
 static ast_t* get_package_scope(pass_opt_t* opt, ast_t* scope, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_NOMINAL);
+  pony_assert(ast_id(ast) == TK_NOMINAL);
   ast_t* package_id = ast_child(ast);
 
   // Find our actual package.
diff --git a/src/libponyc/pass/pass.c b/src/libponyc/pass/pass.c
index 1955a38964c..73f7ed3867b 100644
--- a/src/libponyc/pass/pass.c
+++ b/src/libponyc/pass/pass.c
@@ -14,10 +14,10 @@
 #include "docgen.h"
 #include "../codegen/codegen.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 
 #include <string.h>
 #include <stdbool.h>
-#include <assert.h>
 
 
 bool limit_passes(pass_opt_t* opt, const char* pass)
@@ -132,9 +132,9 @@ void pass_opt_done(pass_opt_t* options)
 static bool check_limit(ast_t** astp, pass_opt_t* options, pass_id pass,
   pass_id last_pass)
 {
-  assert(astp != NULL);
-  assert(*astp != NULL);
-  assert(options != NULL);
+  pony_assert(astp != NULL);
+  pony_assert(*astp != NULL);
+  pony_assert(options != NULL);
 
   if(last_pass < pass || options->limit < pass)
     return false;
@@ -152,7 +152,7 @@ static bool check_limit(ast_t** astp, pass_opt_t* options, pass_id pass,
 static bool visit_pass(ast_t** astp, pass_opt_t* options, pass_id last_pass,
   bool* out_r, pass_id pass, ast_visit_t pre_fn, ast_visit_t post_fn)
 {
-  assert(out_r != NULL);
+  pony_assert(out_r != NULL);
 
   if(!check_limit(astp, options, pass, last_pass))
   {
@@ -195,7 +195,7 @@ bool module_passes(ast_t* package, pass_opt_t* options, source_t* source)
 // Peform the AST passes on the given AST up to the specified last pass
 static bool ast_passes(ast_t** astp, pass_opt_t* options, pass_id last)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   bool r;
 
   if(!visit_pass(astp, options, last, &r, PASS_SUGAR, pass_sugar, NULL))
@@ -254,7 +254,7 @@ bool ast_passes_type(ast_t** astp, pass_opt_t* options)
 {
   ast_t* ast = *astp;
 
-  assert(ast_id(ast) == TK_ACTOR || ast_id(ast) == TK_CLASS ||
+  pony_assert(ast_id(ast) == TK_ACTOR || ast_id(ast) == TK_CLASS ||
     ast_id(ast) == TK_STRUCT || ast_id(ast) == TK_PRIMITIVE ||
     ast_id(ast) == TK_TRAIT || ast_id(ast) == TK_INTERFACE);
 
@@ -294,7 +294,7 @@ bool generate_passes(ast_t* program, pass_opt_t* options)
 
 static void record_ast_pass(ast_t* ast, pass_id pass)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   if(pass == PASS_ALL)
     return;
@@ -307,8 +307,8 @@ static void record_ast_pass(ast_t* ast, pass_id pass)
 ast_result_t ast_visit(ast_t** ast, ast_visit_t pre, ast_visit_t post,
   pass_opt_t* options, pass_id pass)
 {
-  assert(ast != NULL);
-  assert(*ast != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(*ast != NULL);
 
   pass_id ast_pass = (pass_id)ast_checkflag(*ast, AST_FLAG_PASS_MASK);
 
@@ -358,7 +358,7 @@ ast_result_t ast_visit(ast_t** ast, ast_visit_t pre, ast_visit_t post,
 
         case AST_IGNORE:
           // Can never happen
-          assert(0);
+          pony_assert(0);
           break;
 
         case AST_ERROR:
@@ -406,8 +406,8 @@ ast_result_t ast_visit_scope(ast_t** ast, ast_visit_t pre, ast_visit_t post,
   typecheck_t* t = &options->check;
   ast_t* module = ast_nearest(*ast, TK_MODULE);
   ast_t* package = ast_parent(module);
-  assert(module != NULL);
-  assert(package != NULL);
+  pony_assert(module != NULL);
+  pony_assert(package != NULL);
 
   frame_push(t, NULL);
   frame_push(t, package);
diff --git a/src/libponyc/pass/scope.c b/src/libponyc/pass/scope.c
index aea01ac9a71..68f4184c837 100644
--- a/src/libponyc/pass/scope.c
+++ b/src/libponyc/pass/scope.c
@@ -7,8 +7,8 @@
 #include "../ast/stringtab.h"
 #include "../ast/astbuild.h"
 #include "../ast/id.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 /**
  * Insert a name->AST mapping into the specified scope.
@@ -16,7 +16,7 @@
 static bool set_scope(pass_opt_t* opt, typecheck_t* t, ast_t* scope,
   ast_t* name, ast_t* value)
 {
-  assert(ast_id(name) == TK_ID);
+  pony_assert(ast_id(name) == TK_ID);
   const char* s = ast_name(name);
 
   if(is_name_dontcare(s))
@@ -61,7 +61,7 @@ static bool set_scope(pass_opt_t* opt, typecheck_t* t, ast_t* scope,
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -84,8 +84,8 @@ static bool set_scope(pass_opt_t* opt, typecheck_t* t, ast_t* scope,
 bool use_package(ast_t* ast, const char* path, ast_t* name,
   pass_opt_t* options)
 {
-  assert(ast != NULL);
-  assert(path != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(path != NULL);
 
   ast_t* package = package_load(ast, path, options);
 
@@ -106,7 +106,7 @@ bool use_package(ast_t* ast, const char* path, ast_t* name,
 
 static void set_fields_undefined(ast_t* ast)
 {
-  assert(ast_id(ast) == TK_NEW);
+  pony_assert(ast_id(ast) == TK_NEW);
 
   ast_t* members = ast_parent(ast);
   ast_t* member = ast_child(members);
@@ -175,7 +175,7 @@ static ast_result_t scope_entity(pass_opt_t* opt, typecheck_t* t, ast_t* ast)
         break;
 
       default:
-        assert(0);
+        pony_assert(0);
         return AST_FATAL;
     }
 
diff --git a/src/libponyc/pass/sugar.c b/src/libponyc/pass/sugar.c
index e3993088603..56a79a69c03 100644
--- a/src/libponyc/pass/sugar.c
+++ b/src/libponyc/pass/sugar.c
@@ -12,14 +12,14 @@
 #include "../ast/stringtab.h"
 #include "../ast/token.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdio.h>
 #include <string.h>
-#include <assert.h>
 
 
 static ast_t* make_create(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   // Default constructors on classes can be iso, on actors they must be tag
   token_id cap = TK_NONE;
@@ -85,7 +85,7 @@ bool has_member(ast_t* members, const char* name)
 
 static void add_default_constructor(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   ast_t* members = ast_childidx(ast, 4);
 
   // If we have no constructors and no "create" member, add a "create"
@@ -117,7 +117,7 @@ static ast_result_t sugar_module(pass_opt_t* opt, ast_t* ast)
   ast_t* docstring = ast_child(ast);
 
   ast_t* package = ast_parent(ast);
-  assert(ast_id(package) == TK_PACKAGE);
+  pony_assert(ast_id(package) == TK_PACKAGE);
 
   if(strcmp(package_name(package), "$0") != 0)
   {
@@ -213,7 +213,7 @@ static ast_result_t sugar_entity(pass_opt_t* opt, ast_t* ast, bool add_create,
           AST_GET_CHILDREN(member, n_cap, n_id, n_typeparam, n_params,
             n_result, n_partial, n_body);
 
-          assert(ast_id(n_body) == TK_SEQ);
+          pony_assert(ast_id(n_body) == TK_SEQ);
 
           ast_t* init = ast_child(init_seq);
 
@@ -259,7 +259,7 @@ static ast_result_t sugar_typeparam(ast_t* ast)
 
 static void sugar_docstring(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   AST_GET_CHILDREN(ast, cap, id, type_params, params, return_type,
     error, body, docstring);
@@ -285,7 +285,7 @@ static void sugar_docstring(ast_t* ast)
 // something nasty let in by the case method value parsing.
 static ast_result_t check_params(pass_opt_t* opt, ast_t* params)
 {
-  assert(params != NULL);
+  pony_assert(params != NULL);
   ast_result_t result = AST_OK;
 
   // Check each parameter.
@@ -320,7 +320,7 @@ static ast_result_t check_params(pass_opt_t* opt, ast_t* params)
 // Check for leftover stuff from case methods.
 static ast_result_t check_method(pass_opt_t* opt, ast_t* method)
 {
-  assert(method != NULL);
+  pony_assert(method != NULL);
 
   ast_result_t result = AST_OK;
   ast_t* params = ast_childidx(method, 3);
@@ -328,7 +328,7 @@ static ast_result_t check_method(pass_opt_t* opt, ast_t* method)
 
   // Also check the guard expression doesn't exist.
   ast_t* guard = ast_childidx(method, 8);
-  assert(guard != NULL);
+  pony_assert(guard != NULL);
 
   if(ast_id(guard) != TK_NONE)
   {
@@ -390,7 +390,7 @@ static ast_result_t sugar_be(pass_opt_t* opt, ast_t* ast)
 
 void fun_defaults(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   AST_GET_CHILDREN(ast, cap, id, typeparams, params, result, can_error, body,
     docstring);
 
@@ -449,7 +449,7 @@ static ast_result_t sugar_return(pass_opt_t* opt, ast_t* ast)
 
   if((ast_id(ast) == TK_RETURN) && (ast_id(opt->check.frame->method) == TK_NEW))
   {
-    assert(ast_id(return_value) == TK_NONE);
+    pony_assert(ast_id(return_value) == TK_NONE);
     ast_setid(return_value, TK_THIS);
   } else {
     expand_none(return_value, false);
@@ -528,14 +528,14 @@ static ast_result_t sugar_for(pass_opt_t* opt, ast_t** astp)
 
 static void build_with_dispose(ast_t* dispose_clause, ast_t* idseq)
 {
-  assert(dispose_clause != NULL);
-  assert(idseq != NULL);
+  pony_assert(dispose_clause != NULL);
+  pony_assert(idseq != NULL);
 
   if(ast_id(idseq) == TK_LET)
   {
     // Just a single variable
     ast_t* id = ast_child(idseq);
-    assert(id != NULL);
+    pony_assert(id != NULL);
 
     // Don't call dispose() on don't cares
     if(is_name_dontcare(ast_name(id)))
@@ -551,7 +551,7 @@ static void build_with_dispose(ast_t* dispose_clause, ast_t* idseq)
   }
 
   // We have a list of variables
-  assert(ast_id(idseq) == TK_TUPLE);
+  pony_assert(ast_id(idseq) == TK_TUPLE);
 
   for(ast_t* p = ast_child(idseq); p != NULL; p = ast_sibling(p))
     build_with_dispose(dispose_clause, p);
@@ -590,7 +590,7 @@ static ast_result_t sugar_with(pass_opt_t* opt, ast_t** astp)
   // Add the "with" variables from each with element
   for(ast_t* p = ast_child(withexpr); p != NULL; p = ast_sibling(p))
   {
-    assert(ast_id(p) == TK_SEQ);
+    pony_assert(ast_id(p) == TK_SEQ);
     AST_GET_CHILDREN(p, idseq, init);
     const char* init_name = package_hygienic_id(&opt->check);
 
@@ -702,8 +702,8 @@ static ast_result_t sugar_case(pass_opt_t* opt, ast_t* ast)
   while(ast_id(next_body) == TK_NONE)
   {
     next = ast_sibling(next);
-    assert(next != NULL);
-    assert(ast_id(next) == TK_CASE);
+    pony_assert(next != NULL);
+    pony_assert(ast_id(next) == TK_CASE);
     next_body = ast_childidx(next, 2);
   }
 
@@ -715,7 +715,7 @@ static ast_result_t sugar_case(pass_opt_t* opt, ast_t* ast)
 static ast_result_t sugar_update(ast_t** astp)
 {
   ast_t* ast = *astp;
-  assert(ast_id(ast) == TK_ASSIGN);
+  pony_assert(ast_id(ast) == TK_ASSIGN);
 
   AST_GET_CHILDREN(ast, value, call);
 
@@ -942,7 +942,7 @@ static ast_result_t sugar_object(pass_opt_t* opt, ast_t** astp)
 static void add_as_type(pass_opt_t* opt, ast_t* type, ast_t* pattern,
   ast_t* body)
 {
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   switch(ast_id(type))
   {
@@ -1025,7 +1025,7 @@ static ast_result_t sugar_as(pass_opt_t* opt, ast_t** astp)
   }
 
   // Don't need top sequence in pattern
-  assert(ast_id(ast_child(pattern_root)) == TK_SEQ);
+  pony_assert(ast_id(ast_child(pattern_root)) == TK_SEQ);
   ast_t* pattern = ast_pop(ast_child(pattern_root));
   ast_free(pattern_root);
 
@@ -1123,8 +1123,8 @@ static ast_result_t sugar_ffi(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t sugar_ifdef(pass_opt_t* opt, ast_t* ast)
 {
-  assert(opt != NULL);
-  assert(ast != NULL);
+  pony_assert(opt != NULL);
+  pony_assert(ast != NULL);
 
   AST_GET_CHILDREN(ast, cond, then_block, else_block, else_cond);
 
@@ -1134,7 +1134,7 @@ static ast_result_t sugar_ifdef(pass_opt_t* opt, ast_t* ast)
   if(parent_ifdef_cond != NULL)
   {
     // We have a parent ifdef, combine its condition with ours.
-    assert(ast_id(ast_parent(parent_ifdef_cond)) == TK_IFDEF);
+    pony_assert(ast_id(ast_parent(parent_ifdef_cond)) == TK_IFDEF);
 
     REPLACE(&else_cond,
       NODE(TK_AND,
@@ -1172,7 +1172,7 @@ static ast_result_t sugar_ifdef(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t sugar_use(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   // Normalise condition so and, or and not nodes aren't sugared to function
   // calls.
@@ -1191,10 +1191,10 @@ static ast_result_t sugar_use(pass_opt_t* opt, ast_t* ast)
 static ast_result_t sugar_semi(pass_opt_t* options, ast_t** astp)
 {
   ast_t* ast = *astp;
-  assert(ast_id(ast) == TK_SEMI);
+  pony_assert(ast_id(ast) == TK_SEMI);
 
   // Semis are pointless, discard them
-  assert(ast_child(ast) == NULL);
+  pony_assert(ast_child(ast) == NULL);
   *astp = ast_sibling(ast);
   ast_remove(ast);
 
@@ -1206,9 +1206,9 @@ static ast_result_t sugar_semi(pass_opt_t* options, ast_t** astp)
 
 static ast_result_t sugar_lambdatype(pass_opt_t* opt, ast_t** astp)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   ast_t* ast = *astp;
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   AST_EXTRACT_CHILDREN(ast, apply_cap, apply_name, apply_t_params, params,
     ret_type, error, interface_cap, ephemeral);
@@ -1321,7 +1321,7 @@ static ast_result_t sugar_lambdatype(pass_opt_t* opt, ast_t** astp)
 
 ast_t* expand_location(ast_t* location)
 {
-  assert(location != NULL);
+  pony_assert(location != NULL);
 
   const char* file_name = ast_source(location)->file;
 
@@ -1378,9 +1378,9 @@ ast_t* expand_location(ast_t* location)
 
 static ast_result_t sugar_location(pass_opt_t* opt, ast_t** astp)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   ast_t* ast = *astp;
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   if(ast_id(ast_parent(ast)) == TK_PARAM)
     // Location is a default argument, do not expand yet.
@@ -1400,7 +1400,7 @@ static ast_result_t sugar_location(pass_opt_t* opt, ast_t** astp)
 ast_result_t pass_sugar(ast_t** astp, pass_opt_t* options)
 {
   ast_t* ast = *astp;
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   switch(ast_id(ast))
   {
diff --git a/src/libponyc/pass/syntax.c b/src/libponyc/pass/syntax.c
index a64374c751e..fb43fa10a00 100644
--- a/src/libponyc/pass/syntax.c
+++ b/src/libponyc/pass/syntax.c
@@ -7,7 +7,7 @@
 #include "../pkg/platformfuns.h"
 #include "../type/assemble.h"
 #include "../../libponyrt/mem/pool.h"
-#include <assert.h>
+#include "ponyassert.h"
 #include <string.h>
 #include <ctype.h>
 
@@ -145,8 +145,8 @@ static bool is_expr_infix(token_id id)
 static bool check_provides_type(pass_opt_t* opt, ast_t* type,
   const char* description)
 {
-  assert(type != NULL);
-  assert(description != NULL);
+  pony_assert(type != NULL);
+  pony_assert(description != NULL);
 
   switch(ast_id(type))
   {
@@ -194,13 +194,13 @@ static bool check_provides_type(pass_opt_t* opt, ast_t* type,
 static bool check_permission(pass_opt_t* opt, const permission_def_t* def,
   int element, ast_t* actual, const char* context, ast_t* report_at)
 {
-  assert(def != NULL);
-  assert(actual != NULL);
-  assert(context != NULL);
+  pony_assert(def != NULL);
+  pony_assert(actual != NULL);
+  pony_assert(context != NULL);
 
   char permission = def->permissions[element];
 
-  assert(permission == 'Y' || permission == 'N' || permission == 'X');
+  pony_assert(permission == 'Y' || permission == 'N' || permission == 'X');
 
   if(permission == 'N' && ast_id(actual) != TK_NONE)
   {
@@ -223,8 +223,8 @@ static bool check_permission(pass_opt_t* opt, const permission_def_t* def,
 // Check whether the given method has any illegal parts
 static bool check_method(pass_opt_t* opt, ast_t* ast, int method_def_index)
 {
-  assert(ast != NULL);
-  assert(method_def_index >= 0 && method_def_index < DEF_METHOD_COUNT);
+  pony_assert(ast != NULL);
+  pony_assert(method_def_index >= 0 && method_def_index < DEF_METHOD_COUNT);
   bool r = true;
 
   const permission_def_t* def = &_method_def[method_def_index];
@@ -271,8 +271,8 @@ static bool check_method(pass_opt_t* opt, ast_t* ast, int method_def_index)
 // Check whether the given entity members are legal in their entity
 static bool check_members(pass_opt_t* opt, ast_t* members, int entity_def_index)
 {
-  assert(members != NULL);
-  assert(entity_def_index >= 0 && entity_def_index < DEF_ENTITY_COUNT);
+  pony_assert(members != NULL);
+  pony_assert(entity_def_index >= 0 && entity_def_index < DEF_ENTITY_COUNT);
   bool r = true;
 
   const permission_def_t* def = &_entity_def[entity_def_index];
@@ -328,7 +328,7 @@ static bool check_members(pass_opt_t* opt, ast_t* members, int entity_def_index)
 
       default:
         ast_print(members);
-        assert(0);
+        pony_assert(0);
         return false;
     }
 
@@ -343,8 +343,8 @@ static bool check_members(pass_opt_t* opt, ast_t* members, int entity_def_index)
 static ast_result_t syntax_entity(pass_opt_t* opt, ast_t* ast,
   int entity_def_index)
 {
-  assert(ast != NULL);
-  assert(entity_def_index >= 0 && entity_def_index < DEF_ENTITY_COUNT);
+  pony_assert(ast != NULL);
+  pony_assert(entity_def_index >= 0 && entity_def_index < DEF_ENTITY_COUNT);
   ast_result_t r = AST_OK;
 
   const permission_def_t* def = &_entity_def[entity_def_index];
@@ -405,9 +405,9 @@ static ast_result_t syntax_entity(pass_opt_t* opt, ast_t* ast,
 
 static ast_result_t syntax_thistype(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   ast_t* parent = ast_parent(ast);
-  assert(parent != NULL);
+  pony_assert(parent != NULL);
   ast_result_t r = AST_OK;
 
   if(ast_id(parent) != TK_ARROW)
@@ -444,7 +444,7 @@ static ast_result_t syntax_thistype(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t syntax_arrowtype(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   AST_GET_CHILDREN(ast, left, right);
 
   switch(ast_id(right))
@@ -473,7 +473,7 @@ static ast_result_t syntax_arrowtype(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t syntax_nominal(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   AST_GET_CHILDREN(ast, package, name, typeargs, cap, eph);
 
   if(!is_name_dontcare(ast_name(name)))
@@ -515,12 +515,12 @@ static ast_result_t syntax_nominal(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t syntax_match(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   // The last case must have a body
   ast_t* cases = ast_childidx(ast, 1);
-  assert(cases != NULL);
-  assert(ast_id(cases) == TK_CASES);
+  pony_assert(cases != NULL);
+  pony_assert(ast_id(cases) == TK_CASES);
 
   ast_t* case_ast = ast_child(cases);
 
@@ -546,7 +546,7 @@ static ast_result_t syntax_match(pass_opt_t* opt, ast_t* ast)
 static ast_result_t syntax_ffi(pass_opt_t* opt, ast_t* ast,
   bool return_optional)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   AST_GET_CHILDREN(ast, id, typeargs, args, named_args);
   ast_result_t r = AST_OK;
 
@@ -565,7 +565,7 @@ static ast_result_t syntax_ffi(pass_opt_t* opt, ast_t* ast,
     if(ast_id(p) == TK_PARAM)
     {
       ast_t* def_val = ast_childidx(p, 2);
-      assert(def_val != NULL);
+      pony_assert(def_val != NULL);
 
       if(ast_id(def_val) != TK_NONE)
       {
@@ -588,11 +588,11 @@ static ast_result_t syntax_ffi(pass_opt_t* opt, ast_t* ast,
 
 static ast_result_t syntax_ellipsis(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   ast_result_t r = AST_OK;
 
   ast_t* fn = ast_parent(ast_parent(ast));
-  assert(fn != NULL);
+  pony_assert(fn != NULL);
 
   if(ast_id(fn) != TK_FFIDECL)
   {
@@ -613,17 +613,17 @@ static ast_result_t syntax_ellipsis(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t syntax_infix_expr(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   AST_GET_CHILDREN(ast, left, right);
 
   token_id op = ast_id(ast);
 
-  assert(left != NULL);
+  pony_assert(left != NULL);
   token_id left_op = ast_id(left);
   bool left_clash = (left_op != op) && is_expr_infix(left_op) &&
     !ast_checkflag(left, AST_FLAG_IN_PARENS);
 
-  assert(right != NULL);
+  pony_assert(right != NULL);
   token_id right_op = ast_id(right);
   bool right_clash = (right_op != op) && is_expr_infix(right_op) &&
     !ast_checkflag(right, AST_FLAG_IN_PARENS);
@@ -661,10 +661,10 @@ static ast_result_t syntax_consume(pass_opt_t* opt, ast_t* ast)
 static ast_result_t syntax_return(pass_opt_t* opt, ast_t* ast,
   size_t max_value_count)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   ast_t* value_seq = ast_child(ast);
-  assert(ast_id(value_seq) == TK_SEQ || ast_id(value_seq) == TK_NONE);
+  pony_assert(ast_id(value_seq) == TK_SEQ || ast_id(value_seq) == TK_NONE);
   size_t value_count = ast_childcount(value_seq);
 
   if(value_count > max_value_count)
@@ -720,8 +720,8 @@ static ast_result_t syntax_return(pass_opt_t* opt, ast_t* ast,
 
 static ast_result_t syntax_semi(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_parent(ast) != NULL);
-  assert(ast_id(ast_parent(ast)) == TK_SEQ);
+  pony_assert(ast_parent(ast) != NULL);
+  pony_assert(ast_id(ast_parent(ast)) == TK_SEQ);
 
   if(ast_checkflag(ast, AST_FLAG_BAD_SEMI))
   {
@@ -779,8 +779,8 @@ static const char* _illegal_flags[] =
 // such as "ifdef condition" or "use guard".
 static bool syntax_ifdef_cond(pass_opt_t* opt, ast_t* ast, const char* context)
 {
-  assert(ast != NULL);
-  assert(context != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(context != NULL);
 
   switch(ast_id(ast))
   {
@@ -866,7 +866,7 @@ static bool syntax_ifdef_cond(pass_opt_t* opt, ast_t* ast, const char* context)
 
 static ast_result_t syntax_ifdef(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   if(!syntax_ifdef_cond(opt, ast_child(ast), "ifdef condition"))
     return AST_ERROR;
@@ -877,7 +877,7 @@ static ast_result_t syntax_ifdef(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t syntax_use(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
   AST_GET_CHILDREN(ast, id, url, guard);
 
   if(ast_id(id) != TK_NONE && !check_id_package(opt, id))
@@ -908,7 +908,7 @@ static ast_result_t syntax_lambda_capture(pass_opt_t* opt, ast_t* ast)
 static ast_result_t syntax_compile_intrinsic(pass_opt_t* opt, ast_t* ast)
 {
   ast_t* parent = ast_parent(ast);
-  assert(ast_id(parent) == TK_SEQ);
+  pony_assert(ast_id(parent) == TK_SEQ);
 
   ast_t* method = ast_parent(parent);
 
@@ -949,7 +949,7 @@ static ast_result_t syntax_compile_intrinsic(pass_opt_t* opt, ast_t* ast)
 static ast_result_t syntax_compile_error(pass_opt_t* opt, ast_t* ast)
 {
   ast_t* parent = ast_parent(ast);
-  assert(ast_id(parent) == TK_SEQ);
+  pony_assert(ast_id(parent) == TK_SEQ);
 
   if(ast_id(ast_parent(parent)) != TK_IFDEF)
   {
@@ -985,7 +985,7 @@ static ast_result_t syntax_compile_error(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t syntax_lambda(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_LAMBDA);
+  pony_assert(ast_id(ast) == TK_LAMBDA);
   AST_GET_CHILDREN(ast, receiver_cap, name, t_params, params, captures,
     ret_type, raises, body, reference_cap);
   switch(ast_id(ret_type))
@@ -1031,7 +1031,7 @@ static ast_result_t syntax_lambda(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t syntax_object(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_OBJECT);
+  pony_assert(ast_id(ast) == TK_OBJECT);
   AST_GET_CHILDREN(ast, cap, provides, members);
 
   // Check for illegal members - even though object literals can be non-actors,
@@ -1045,7 +1045,7 @@ static ast_result_t syntax_object(pass_opt_t* opt, ast_t* ast)
 
 static ast_result_t syntax_fun(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_FUN);
+  pony_assert(ast_id(ast) == TK_FUN);
   AST_GET_CHILDREN(ast, cap, id, typeparams, params, type, can_error, body);
   switch(ast_id(type))
   {
@@ -1116,9 +1116,9 @@ static ast_result_t syntax_cap_set(pass_opt_t* opt, ast_t* ast)
 
 ast_result_t pass_syntax(ast_t** astp, pass_opt_t* options)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
   ast_t* ast = *astp;
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   token_id id = ast_id(ast);
   ast_result_t r = AST_OK;
diff --git a/src/libponyc/pass/traits.c b/src/libponyc/pass/traits.c
index 639da9c6cef..82fd6501631 100644
--- a/src/libponyc/pass/traits.c
+++ b/src/libponyc/pass/traits.c
@@ -8,7 +8,7 @@
 #include "../type/subtype.h"
 #include "../type/reify.h"
 #include "../../libponyrt/mem/pool.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 
 /** The following defines how we determine the signature and body to use for
@@ -66,7 +66,7 @@ static bool trait_entity(ast_t* entity, pass_opt_t* options);
 // Report whether the given node is a method.
 static bool is_method(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   token_id variety = ast_id(ast);
   return (variety == TK_BE) || (variety == TK_FUN) || (variety == TK_NEW);
@@ -76,7 +76,7 @@ static bool is_method(ast_t* ast)
 // Attach a new method_t structure to the given method.
 static method_t* attach_method_t(ast_t* method)
 {
-  assert(method != NULL);
+  pony_assert(method != NULL);
 
   method_t* p = POOL_ALLOC(method_t);
   p->body_donor = NULL;
@@ -92,10 +92,10 @@ static method_t* attach_method_t(ast_t* method)
 // Setup a method_t structure for each method in the given type.
 static void setup_local_methods(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   ast_t* members = ast_childidx(ast, 4);
-  assert(members != NULL);
+  pony_assert(members != NULL);
 
   for(ast_t* p = ast_child(members); p != NULL; p = ast_sibling(p))
   {
@@ -114,17 +114,17 @@ static void setup_local_methods(ast_t* ast)
 // Tidy up the method_t structures in the given entity.
 static void tidy_up(ast_t* entity)
 {
-  assert(entity != NULL);
+  pony_assert(entity != NULL);
 
   ast_t* members = ast_childidx(entity, 4);
-  assert(members != NULL);
+  pony_assert(members != NULL);
 
   for(ast_t* p = ast_child(members); p != NULL; p = ast_sibling(p))
   {
     if(is_method(p))
     {
       method_t* info = (method_t*)ast_data(p);
-      assert(info != NULL);
+      pony_assert(info != NULL);
       ast_t* body_donor = info->body_donor;
       POOL_FREE(method_t, info);
 
@@ -238,13 +238,13 @@ static bool compare_signatures(ast_t* sig_a, ast_t* sig_b)
 static ast_t* reify_provides_type(ast_t* method, ast_t* trait_ref,
   pass_opt_t* opt)
 {
-  assert(method != NULL);
-  assert(trait_ref != NULL);
+  pony_assert(method != NULL);
+  pony_assert(trait_ref != NULL);
 
   // Apply the type args (if any) from the trait reference to the type
   // parameters from the trait definition.
   ast_t* trait_def = (ast_t*)ast_data(trait_ref);
-  assert(trait_def != NULL);
+  pony_assert(trait_def != NULL);
   ast_t* type_args = ast_childidx(trait_ref, 2);
   ast_t* type_params = ast_childidx(trait_def, 1);
 
@@ -268,8 +268,8 @@ static ast_t* reify_provides_type(ast_t* method, ast_t* trait_ref,
 // Return the method with the specified name or NULL if not found.
 static ast_t* find_method(ast_t* entity, const char* name)
 {
-  assert(entity != NULL);
-  assert(name != NULL);
+  pony_assert(entity != NULL);
+  pony_assert(name != NULL);
 
   ast_t* method = ast_get(entity, name, NULL);
 
@@ -294,10 +294,10 @@ static ast_t* find_method(ast_t* entity, const char* name)
 static ast_t* add_method(ast_t* entity, ast_t* trait_ref, ast_t* basis_method,
   const char* adjective, pass_opt_t* opt)
 {
-  assert(entity != NULL);
-  assert(trait_ref != NULL);
-  assert(basis_method != NULL);
-  assert(adjective != NULL);
+  pony_assert(entity != NULL);
+  pony_assert(trait_ref != NULL);
+  pony_assert(basis_method != NULL);
+  pony_assert(adjective != NULL);
 
   const char* name = ast_name(ast_childidx(basis_method, 1));
 
@@ -334,7 +334,7 @@ static ast_t* add_method(ast_t* entity, ast_t* trait_ref, ast_t* basis_method,
     // Should already have checked for methods.
     token_id variety = ast_id(existing);
     (void)variety;
-    assert((variety == TK_FVAR) || (variety == TK_FLET) || (variety == TK_EMBED));
+    pony_assert((variety == TK_FVAR) || (variety == TK_FLET) || (variety == TK_EMBED));
 
     ast_error(opt->check.errors, trait_ref,
       "%s method '%s' clashes with field", adjective, name);
@@ -365,7 +365,7 @@ static ast_t* add_method(ast_t* entity, ast_t* trait_ref, ast_t* basis_method,
         break;
 
       default:
-        assert(0);
+        pony_assert(0);
         break;
     }
 
@@ -417,7 +417,7 @@ static ast_result_t rescope(ast_t** astp, pass_opt_t* options)
     case TK_PARAM:
     case TK_TYPEPARAM:
     {
-      assert(ast_child(ast) != NULL);
+      pony_assert(ast_child(ast) != NULL);
       ast_set(ast, ast_name(ast_child(ast)), ast, SYM_DEFINED, true);
       break;
     }
@@ -441,7 +441,7 @@ static ast_result_t rescope(ast_t** astp, pass_opt_t* options)
 
     case TK_TYPEPARAMREF:
     {
-      assert(ast_child(ast) != NULL);
+      pony_assert(ast_child(ast) != NULL);
       ast_t* def = ast_get(ast, ast_name(ast_child(ast)), NULL);
       ast_setdata(ast, def);
       break;
@@ -464,9 +464,9 @@ static ast_result_t rescope(ast_t** astp, pass_opt_t* options)
 static bool add_method_from_trait(ast_t* entity, ast_t* method,
   ast_t* trait_ref, pass_opt_t* opt)
 {
-  assert(entity != NULL);
-  assert(method != NULL);
-  assert(trait_ref != NULL);
+  pony_assert(entity != NULL);
+  pony_assert(method != NULL);
+  pony_assert(trait_ref != NULL);
 
   AST_GET_CHILDREN(method, cap, id, t_params, params, result, error,
     method_body);
@@ -490,7 +490,7 @@ static bool add_method_from_trait(ast_t* entity, ast_t* method,
 
   // A method with this name already exists.
   method_t* info = (method_t*)ast_data(existing_method);
-  assert(info != NULL);
+  pony_assert(info != NULL);
 
   // Method has already caused an error, do nothing.
   if(info->failed)
@@ -502,7 +502,7 @@ static bool add_method_from_trait(ast_t* entity, ast_t* method,
   // Existing method is also provided, signatures must match exactly.
   if(!compare_signatures(existing_method, method))
   {
-    assert(info->trait_ref != NULL);
+    pony_assert(info->trait_ref != NULL);
 
     ast_error(opt->check.errors, trait_ref,
       "clashing definitions for method '%s' provided, local disambiguation "
@@ -547,7 +547,7 @@ static bool add_method_from_trait(ast_t* entity, ast_t* method,
     return true;
 
   // Trait provides default body. Use it and patch up symbol tables.
-  assert(ast_id(existing_body) == TK_NONE);
+  pony_assert(ast_id(existing_body) == TK_NONE);
   ast_replace(&existing_body, method_body);
   ast_visit(&method_body, rescope, NULL, opt, PASS_ALL);
 
@@ -561,7 +561,7 @@ static bool add_method_from_trait(ast_t* entity, ast_t* method,
 // provides list.
 static bool provided_methods(ast_t* entity, pass_opt_t* opt)
 {
-  assert(entity != NULL);
+  pony_assert(entity != NULL);
 
   ast_t* provides = ast_childidx(entity, 3);
   bool r = true;
@@ -571,7 +571,7 @@ static bool provided_methods(ast_t* entity, pass_opt_t* opt)
     trait_ref = ast_sibling(trait_ref))
   {
     ast_t* trait = (ast_t*)ast_data(trait_ref);
-    assert(trait != NULL);
+    pony_assert(trait != NULL);
 
     if(!trait_entity(trait, opt))
       return false;
@@ -582,7 +582,7 @@ static bool provided_methods(ast_t* entity, pass_opt_t* opt)
     for(ast_t* method = ast_child(members); method != NULL;
       method = ast_sibling(method))
     {
-      assert(is_method(method));
+      pony_assert(is_method(method));
 
       ast_t* reified = reify_provides_type(method, trait_ref, opt);
 
@@ -608,7 +608,7 @@ static bool provided_methods(ast_t* entity, pass_opt_t* opt)
 // Check that the given entity, if concrete, has bodies for all methods.
 static bool check_concrete_bodies(ast_t* entity, pass_opt_t* opt)
 {
-  assert(entity != NULL);
+  pony_assert(entity != NULL);
 
   token_id variety = ast_id(entity);
   if((variety != TK_PRIMITIVE) && (variety != TK_STRUCT) &&
@@ -617,14 +617,14 @@ static bool check_concrete_bodies(ast_t* entity, pass_opt_t* opt)
 
   bool r = true;
   ast_t* members = ast_childidx(entity, 4);
-  assert(members != NULL);
+  pony_assert(members != NULL);
 
   for(ast_t* p = ast_child(members); p != NULL; p = ast_sibling(p))
   {
     if(is_method(p))
     {
       method_t* info = (method_t*)ast_data(p);
-      assert(info != NULL);
+      pony_assert(info != NULL);
 
       if(!info->failed)
       {
@@ -640,7 +640,7 @@ static bool check_concrete_bodies(ast_t* entity, pass_opt_t* opt)
         else if(info->body_donor == NULL)
         {
           // Concrete types must have method bodies.
-          assert(info->trait_ref != NULL);
+          pony_assert(info->trait_ref != NULL);
           ast_error(opt->check.errors, info->trait_ref,
             "no body found for method '%s'", name);
           r = false;
@@ -656,7 +656,7 @@ static bool check_concrete_bodies(ast_t* entity, pass_opt_t* opt)
 // Add provided methods to the given entity.
 static bool trait_entity(ast_t* entity, pass_opt_t* opt)
 {
-  assert(entity != NULL);
+  pony_assert(entity != NULL);
 
   int state = ast_checkflag(entity,
     AST_FLAG_RECURSE_1 | AST_FLAG_DONE_1 | AST_FLAG_ERROR_1);
@@ -682,7 +682,7 @@ static bool trait_entity(ast_t* entity, pass_opt_t* opt)
       return false;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -703,7 +703,7 @@ static bool trait_entity(ast_t* entity, pass_opt_t* opt)
 // Check that embed fields are not recursive.
 static bool embed_fields(ast_t* entity, pass_opt_t* opt)
 {
-  assert(entity != NULL);
+  pony_assert(entity != NULL);
 
   int state = ast_checkflag(entity,
     AST_FLAG_RECURSE_2 | AST_FLAG_DONE_2 | AST_FLAG_ERROR_2);
@@ -729,7 +729,7 @@ static bool embed_fields(ast_t* entity, pass_opt_t* opt)
       return false;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -742,7 +742,7 @@ static bool embed_fields(ast_t* entity, pass_opt_t* opt)
     {
       AST_GET_CHILDREN(member, f_id, f_type);
       ast_t* def = (ast_t*)ast_data(f_type);
-      assert(def != NULL);
+      pony_assert(def != NULL);
 
       if(!embed_fields(def, opt))
         return false;
@@ -763,12 +763,12 @@ static bool embed_fields(ast_t* entity, pass_opt_t* opt)
 // after the name pass (to get temporal capabilities).
 static void local_types(ast_t* ast)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   // Setup type or mark as inferred now to allow calling create on a
   // non-inferred local to initialise itself
   AST_GET_CHILDREN(ast, id, type);
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   if(ast_id(type) == TK_NONE)
   {
@@ -786,7 +786,7 @@ static void local_types(ast_t* ast)
 // Add eq() and ne() functions to the given entity.
 static bool add_comparable(ast_t* ast, pass_opt_t* options)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   AST_GET_CHILDREN(ast, id, typeparams, defcap, traits, members);
   ast_t* typeargs = ast_from(typeparams, TK_NONE);
diff --git a/src/libponyc/pass/verify.c b/src/libponyc/pass/verify.c
index de6eb5993b6..23a18f5d1c5 100644
--- a/src/libponyc/pass/verify.c
+++ b/src/libponyc/pass/verify.c
@@ -2,7 +2,7 @@
 #include "../verify/call.h"
 #include "../verify/control.h"
 #include "../verify/fun.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 ast_result_t pass_verify(ast_t** astp, pass_opt_t* options)
 {
@@ -56,7 +56,7 @@ ast_result_t pass_verify(ast_t** astp, pass_opt_t* options)
 
   if(!r)
   {
-    assert(errors_get_count(options->check.errors) > 0);
+    pony_assert(errors_get_count(options->check.errors) > 0);
     return AST_ERROR;
   }
 
diff --git a/src/libponyc/pkg/buildflagset.c b/src/libponyc/pkg/buildflagset.c
index fd48f64d3fb..3b9a0edb30d 100644
--- a/src/libponyc/pkg/buildflagset.c
+++ b/src/libponyc/pkg/buildflagset.c
@@ -3,8 +3,8 @@
 #include "../ast/stringtab.h"
 #include "../../libponyrt/ds/hash.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 #include <stdio.h>
 
 
@@ -71,21 +71,21 @@ typedef struct flag_t
 // Functions required for our hash table type.
 static size_t flag_hash(flag_t* flag)
 {
-  assert(flag != NULL);
+  pony_assert(flag != NULL);
   return ponyint_hash_ptr(flag->name);
 }
 
 static bool flag_cmp(flag_t* a, flag_t* b)
 {
-  assert(a != NULL);
-  assert(b != NULL);
+  pony_assert(a != NULL);
+  pony_assert(b != NULL);
 
   return a->name == b->name;
 }
 
 static flag_t* flag_dup(flag_t* flag)
 {
-  assert(flag != NULL);
+  pony_assert(flag != NULL);
 
   flag_t* f = POOL_ALLOC(flag_t);
   memcpy(f, flag, sizeof(flag_t));
@@ -94,7 +94,7 @@ static flag_t* flag_dup(flag_t* flag)
 
 static void flag_free(flag_t* flag)
 {
-  assert(flag != NULL);
+  pony_assert(flag != NULL);
   POOL_FREE(flag_t, flag);
 }
 
@@ -122,7 +122,7 @@ struct buildflagset_t
 buildflagset_t* buildflagset_create()
 {
   buildflagset_t* p = POOL_ALLOC(buildflagset_t);
-  assert(p != NULL);
+  pony_assert(p != NULL);
 
   p->have_os_flags = false;
   p->have_arch_flags = false;
@@ -156,7 +156,7 @@ void buildflagset_free(buildflagset_t* set)
 // Returns: index of flag into _os_flags array, or <0 if not an OS flag.
 static ssize_t os_index(const char* flag)
 {
-  assert(flag != NULL);
+  pony_assert(flag != NULL);
 
   stringtab_mutexgroups();
 
@@ -173,7 +173,7 @@ static ssize_t os_index(const char* flag)
 // Returns: index of flag into _arch_flags array, or <0 if not an arch flag.
 static ssize_t arch_index(const char* flag)
 {
-  assert(flag != NULL);
+  pony_assert(flag != NULL);
 
   stringtab_mutexgroups();
 
@@ -190,7 +190,7 @@ static ssize_t arch_index(const char* flag)
 // Returns: index of flag into _size_flags array, or <0 if not a size flag.
 static ssize_t size_index(const char* flag)
 {
-  assert(flag != NULL);
+  pony_assert(flag != NULL);
 
   stringtab_mutexgroups();
 
@@ -205,10 +205,10 @@ static ssize_t size_index(const char* flag)
 
 void buildflagset_add(buildflagset_t* set, const char* flag)
 {
-  assert(set != NULL);
-  assert(flag != NULL);
-  assert(set->flags != NULL);
-  assert(!set->started_enum);
+  pony_assert(set != NULL);
+  pony_assert(flag != NULL);
+  pony_assert(set->flags != NULL);
+  pony_assert(!set->started_enum);
 
   // First check for mutually exclusive groups.
   if(os_index(flag) >= 0)
@@ -249,8 +249,8 @@ void buildflagset_add(buildflagset_t* set, const char* flag)
 
 double buildflagset_configcount(buildflagset_t* set)
 {
-  assert(set != NULL);
-  assert(set->flags != NULL);
+  pony_assert(set != NULL);
+  pony_assert(set->flags != NULL);
 
   double r = 1.0;
 
@@ -294,8 +294,8 @@ double buildflagset_configcount(buildflagset_t* set)
 
 void buildflagset_startenum(buildflagset_t* set)
 {
-  assert(set != NULL);
-  assert(set->flags != NULL);
+  pony_assert(set != NULL);
+  pony_assert(set->flags != NULL);
 
   set->started_enum = true;
   set->first_config_ready = true;
@@ -315,9 +315,9 @@ void buildflagset_startenum(buildflagset_t* set)
 
 bool buildflagset_next(buildflagset_t* set)
 {
-  assert(set != NULL);
-  assert(set->flags != NULL);
-  assert(set->started_enum);
+  pony_assert(set != NULL);
+  pony_assert(set->flags != NULL);
+  pony_assert(set->started_enum);
 
   if(set->first_config_ready)
   {
@@ -383,10 +383,10 @@ bool buildflagset_next(buildflagset_t* set)
 
 bool buildflagset_get(buildflagset_t* set, const char* flag)
 {
-  assert(set != NULL);
-  assert(flag != NULL);
-  assert(set->flags != NULL);
-  assert(set->started_enum);
+  pony_assert(set != NULL);
+  pony_assert(flag != NULL);
+  pony_assert(set->flags != NULL);
+  pony_assert(set->started_enum);
 
   // First check mutually exclusive groups.
   ssize_t index = os_index(flag);
@@ -410,7 +410,7 @@ bool buildflagset_get(buildflagset_t* set, const char* flag)
   flag_t* f2 = flagtab_get(set->flags, &f1, &h_index);
 
   // Flag MUST have been added previously.
-  assert(f2 != NULL);
+  pony_assert(f2 != NULL);
 
   return f2->value;
 }
@@ -421,9 +421,9 @@ bool buildflagset_get(buildflagset_t* set, const char* flag)
 // Advance the location pointer whether the text is written or not.
 static void print_str(const char* s, buildflagset_t* set, char** pointer)
 {
-  assert(s != NULL);
-  assert(set != NULL);
-  assert(pointer != NULL);
+  pony_assert(s != NULL);
+  pony_assert(set != NULL);
+  pony_assert(pointer != NULL);
 
   size_t len = strlen(s);
 
@@ -443,8 +443,8 @@ static void print_str(const char* s, buildflagset_t* set, char** pointer)
 static void print_flag(const char* flag, bool sense, buildflagset_t* set,
   char** pointer)
 {
-  assert(flag != NULL);
-  assert(set != NULL);
+  pony_assert(flag != NULL);
+  pony_assert(set != NULL);
 
   if(*pointer != set->text_buffer)
     print_str(" ", set, pointer);
@@ -458,8 +458,8 @@ static void print_flag(const char* flag, bool sense, buildflagset_t* set,
 
 const char* buildflagset_print(buildflagset_t* set)
 {
-  assert(set != NULL);
-  assert(set->flags != NULL);
+  pony_assert(set != NULL);
+  pony_assert(set->flags != NULL);
 
   char* p = set->text_buffer;
 
@@ -499,7 +499,7 @@ const char* buildflagset_print(buildflagset_t* set)
   }
 
   // Add terminator.
-  assert(set->text_buffer != NULL);
+  pony_assert(set->text_buffer != NULL);
   set->text_buffer[size_needed - 1] = '\0';
   return set->text_buffer;
 }
@@ -509,7 +509,7 @@ static flagtab_t* _user_flags = NULL;
 
 bool define_build_flag(const char* name)
 {
-  assert(name != NULL);
+  pony_assert(name != NULL);
 
   if(_user_flags == NULL)
   {
@@ -535,7 +535,7 @@ bool define_build_flag(const char* name)
 
 bool is_build_flag_defined(const char* name)
 {
-  assert(name != NULL);
+  pony_assert(name != NULL);
 
   if(_user_flags == NULL)
     // Table is not initialised, so no flags are defined.
diff --git a/src/libponyc/pkg/ifdef.c b/src/libponyc/pkg/ifdef.c
index 400a7d82915..432f83a8dab 100644
--- a/src/libponyc/pkg/ifdef.c
+++ b/src/libponyc/pkg/ifdef.c
@@ -6,18 +6,18 @@
 #include "../ast/symtab.h"
 #include "platformfuns.h"
 #include "../pass/pass.h"
+#include "ponyassert.h"
 #include <stdio.h>
-#include <assert.h>
 #include <string.h>
 
 
 // Normalise the given ifdef condition.
 static void cond_normalise(ast_t** astp)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
 
   ast_t* ast = *astp;
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   switch(ast_id(ast))
   {
@@ -82,9 +82,9 @@ static void cond_normalise(ast_t** astp)
     case TK_SEQ:
     {
       // Remove the sequence node.
-      assert(ast_childcount(ast) == 1);
+      pony_assert(ast_childcount(ast) == 1);
       ast_t* child = ast_pop(ast);
-      assert(child != NULL);
+      pony_assert(child != NULL);
 
       cond_normalise(&child);
       ast_replace(astp, child);
@@ -100,7 +100,7 @@ static void cond_normalise(ast_t** astp)
 
     default:
       ast_fprint(stderr, ast);
-      assert(0);
+      pony_assert(0);
       break;
   }
 }
@@ -111,7 +111,7 @@ static void cond_normalise(ast_t** astp)
 static bool cond_eval(ast_t* ast, buildflagset_t* config, bool release,
   pass_opt_t* opt)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   switch(ast_id(ast))
   {
@@ -157,7 +157,7 @@ static bool cond_eval(ast_t* ast, buildflagset_t* config, bool release,
 
     default:
       ast_fprint(stderr, ast);
-      assert(0);
+      pony_assert(0);
       return false;
   }
 }
@@ -166,8 +166,8 @@ static bool cond_eval(ast_t* ast, buildflagset_t* config, bool release,
 // Find the build config flags used in the given ifdef condition.
 static void find_flags_in_cond(ast_t* ast, buildflagset_t* config)
 {
-  assert(ast != NULL);
-  assert(config != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(config != NULL);
 
   switch(ast_id(ast))
   {
@@ -197,7 +197,7 @@ static void find_flags_in_cond(ast_t* ast, buildflagset_t* config)
 
     default:
       ast_fprint(stderr, ast);
-      assert(0);
+      pony_assert(0);
       break;
   }
 }
@@ -208,9 +208,9 @@ static void find_flags_in_cond(ast_t* ast, buildflagset_t* config)
 static bool find_decl_flags(ast_t* package, const char* ffi_name,
   buildflagset_t* config)
 {
-  assert(package != NULL);
-  assert(ffi_name != NULL);
-  assert(config != NULL);
+  pony_assert(package != NULL);
+  pony_assert(ffi_name != NULL);
+  pony_assert(config != NULL);
 
   bool had_decl = false;
 
@@ -259,11 +259,11 @@ static bool find_decl_for_config(ast_t* call, ast_t* package,
   const char* ffi_name, buildflagset_t* config, ffi_decl_t* decl_info,
   pass_opt_t* opt)
 {
-  assert(call != NULL);
-  assert(package != NULL);
-  assert(ffi_name != NULL);
-  assert(config != NULL);
-  assert(decl_info != NULL);
+  pony_assert(call != NULL);
+  pony_assert(package != NULL);
+  pony_assert(ffi_name != NULL);
+  pony_assert(config != NULL);
+  pony_assert(decl_info != NULL);
 
   bool had_valid_decl = false;
 
@@ -331,8 +331,8 @@ static bool find_decl_for_config(ast_t* call, ast_t* package,
 // lot.
 static void check_config_count(buildflagset_t* config, ast_t* location)
 {
-  assert(config != NULL);
-  assert(location != NULL);
+  pony_assert(config != NULL);
+  pony_assert(location != NULL);
 
   double config_count = buildflagset_configcount(config);
 
@@ -359,9 +359,9 @@ static void check_config_count(buildflagset_t* config, ast_t* location)
 static bool find_ffi_decl(ast_t* ast, ast_t* package, ast_t* ifdef_cond,
   ast_t** out_decl, pass_opt_t* opt)
 {
-  assert(ast != NULL);
-  assert(package != NULL);
-  assert(out_decl != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(package != NULL);
+  pony_assert(out_decl != NULL);
 
   const char* ffi_name = ast_name(ast_child(ast));
   buildflagset_t* config = buildflagset_create();
@@ -395,12 +395,12 @@ static bool find_ffi_decl(ast_t* ast, ast_t* package, ast_t* ifdef_cond,
         return false;
       }
 
-      assert(decl_info.decl != NULL);
+      pony_assert(decl_info.decl != NULL);
     }
   }
 
   buildflagset_free(config);
-  assert(decl_info.decl != NULL);
+  pony_assert(decl_info.decl != NULL);
   *out_decl = decl_info.decl;
   return true;
 }
@@ -408,8 +408,8 @@ static bool find_ffi_decl(ast_t* ast, ast_t* package, ast_t* ifdef_cond,
 
 bool ifdef_cond_normalise(ast_t** astp, pass_opt_t* opt)
 {
-  assert(astp != NULL);
-  assert(*astp != NULL);
+  pony_assert(astp != NULL);
+  pony_assert(*astp != NULL);
 
   if(ast_id(*astp) == TK_NONE)  // No condition to normalise.
     return true;
@@ -436,7 +436,7 @@ bool ifdef_cond_normalise(ast_t** astp, pass_opt_t* opt)
 
 bool ifdef_cond_eval(ast_t* ast, pass_opt_t* opt)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   if(ast_id(ast) == TK_NONE)  // No condition to evaluate
     return true;
@@ -448,9 +448,9 @@ bool ifdef_cond_eval(ast_t* ast, pass_opt_t* opt)
 bool ffi_get_decl(typecheck_t* t, ast_t* ast, ast_t** out_decl,
   pass_opt_t* opt)
 {
-  assert(t != NULL);
-  assert(ast != NULL);
-  assert(out_decl != NULL);
+  pony_assert(t != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(out_decl != NULL);
 
   const char* ffi_name = ast_name(ast_child(ast));
 
@@ -458,7 +458,7 @@ bool ffi_get_decl(typecheck_t* t, ast_t* ast, ast_t** out_decl,
   // just search up through scopes as normal since FFI declarations in outer
   // scopes may not be valid within our ifdef.
   ast_t* ifdef = t->frame->ifdef_clause;
-  assert(ifdef != NULL);
+  pony_assert(ifdef != NULL);
 
   symtab_t* symtab = ast_get_symtab(ifdef);
   sym_status_t status;
@@ -471,7 +471,7 @@ bool ffi_get_decl(typecheck_t* t, ast_t* ast, ast_t** out_decl,
   if(status == SYM_NONE)
   {
     // We've not looked that up yet.
-    assert(decl == NULL);
+    pony_assert(decl == NULL);
     if(!find_ffi_decl(ast, t->frame->package, t->frame->ifdef_cond, &decl, opt))
     {
       // That went wrong. Record that so we don't try again.
diff --git a/src/libponyc/pkg/package.c b/src/libponyc/pkg/package.c
index f7821b593dd..e2d06bbfcca 100644
--- a/src/libponyc/pkg/package.c
+++ b/src/libponyc/pkg/package.c
@@ -8,6 +8,7 @@
 #include "../ast/token.h"
 #include "../expr/literal.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdlib.h>
 #include <stdio.h>
 #include <stdbool.h>
@@ -15,7 +16,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <errno.h>
-#include <assert.h>
 
 #if defined(PLATFORM_IS_LINUX)
 #include <unistd.h>
@@ -98,9 +98,9 @@ static magic_package_t* find_magic_package(const char* path)
 static bool parse_source_file(ast_t* package, const char* file_path,
   pass_opt_t* opt)
 {
-  assert(package != NULL);
-  assert(file_path != NULL);
-  assert(opt != NULL);
+  pony_assert(package != NULL);
+  pony_assert(file_path != NULL);
+  pony_assert(opt != NULL);
 
   if(opt->print_filenames)
     printf("Opening %s\n", file_path);
@@ -126,14 +126,14 @@ static bool parse_source_file(ast_t* package, const char* file_path,
 static bool parse_source_code(ast_t* package, const char* src,
   pass_opt_t* opt)
 {
-  assert(src != NULL);
-  assert(opt != NULL);
+  pony_assert(src != NULL);
+  pony_assert(opt != NULL);
 
   if(opt->print_filenames)
     printf("Opening magic source\n");
 
   source_t* source = source_open_string(src);
-  assert(source != NULL);
+  pony_assert(source != NULL);
 
   return module_passes(package, opt, source);
 }
@@ -245,11 +245,11 @@ static const char* try_path(const char* base, const char* path)
 
 static bool is_root(const char* path)
 {
-  assert(path != NULL);
+  pony_assert(path != NULL);
 
 #if defined(PLATFORM_IS_WINDOWS)
-  assert(path[0] != '\0');
-  assert(path[1] == ':');
+  pony_assert(path[0] != '\0');
+  pony_assert(path[1] == ':');
 
   if((path[2] == '\0'))
     return true;
@@ -842,7 +842,7 @@ ast_t* program_load(const char* path, pass_opt_t* opt)
 
 ast_t* package_load(ast_t* from, const char* path, pass_opt_t* opt)
 {
-  assert(from != NULL);
+  pony_assert(from != NULL);
 
   magic_package_t* magic = find_magic_package(path);
   const char* full_path = path;
@@ -955,8 +955,8 @@ ast_t* package_id(ast_t* ast)
 
 const char* package_path(ast_t* package)
 {
-  assert(package != NULL);
-  assert(ast_id(package) == TK_PACKAGE);
+  pony_assert(package != NULL);
+  pony_assert(ast_id(package) == TK_PACKAGE);
   package_t* pkg = (package_t*)ast_data(package);
 
   return pkg->path;
@@ -965,8 +965,8 @@ const char* package_path(ast_t* package)
 
 const char* package_qualified_name(ast_t* package)
 {
-  assert(package != NULL);
-  assert(ast_id(package) == TK_PACKAGE);
+  pony_assert(package != NULL);
+  pony_assert(ast_id(package) == TK_PACKAGE);
   package_t* pkg = (package_t*)ast_data(package);
 
   return pkg->qualified_name;
@@ -975,10 +975,10 @@ const char* package_qualified_name(ast_t* package)
 
 const char* package_filename(ast_t* package)
 {
-  assert(package != NULL);
-  assert(ast_id(package) == TK_PACKAGE);
+  pony_assert(package != NULL);
+  pony_assert(ast_id(package) == TK_PACKAGE);
   package_t* pkg = (package_t*)ast_data(package);
-  assert(pkg != NULL);
+  pony_assert(pkg != NULL);
 
   return pkg->filename;
 }
@@ -986,10 +986,10 @@ const char* package_filename(ast_t* package)
 
 const char* package_symbol(ast_t* package)
 {
-  assert(package != NULL);
-  assert(ast_id(package) == TK_PACKAGE);
+  pony_assert(package != NULL);
+  pony_assert(ast_id(package) == TK_PACKAGE);
   package_t* pkg = (package_t*)ast_data(package);
-  assert(pkg != NULL);
+  pony_assert(pkg != NULL);
 
   return pkg->symbol;
 }
@@ -997,7 +997,7 @@ const char* package_symbol(ast_t* package)
 
 const char* package_hygienic_id(typecheck_t* t)
 {
-  assert(t->frame->package != NULL);
+  pony_assert(t->frame->package != NULL);
   package_t* pkg = (package_t*)ast_data(t->frame->package);
   size_t id = pkg->next_hygienic_id++;
 
@@ -1007,7 +1007,7 @@ const char* package_hygienic_id(typecheck_t* t)
 
 bool package_allow_ffi(typecheck_t* t)
 {
-  assert(t->frame->package != NULL);
+  pony_assert(t->frame->package != NULL);
   package_t* pkg = (package_t*)ast_data(t->frame->package);
   return pkg->allow_ffi;
 }
diff --git a/src/libponyc/pkg/platformfuns.c b/src/libponyc/pkg/platformfuns.c
index be21784a67e..127a3559941 100644
--- a/src/libponyc/pkg/platformfuns.c
+++ b/src/libponyc/pkg/platformfuns.c
@@ -1,15 +1,15 @@
 #include "platformfuns.h"
 #include "../codegen/genopt.h"
-#include <assert.h>
+#include "ponyassert.h"
 #include <string.h>
 
 
 // Report whether the named platform attribute is true
 bool os_is_target(const char* attribute, bool release, bool* out_is_target, pass_opt_t* options)
 {
-  assert(attribute != NULL);
-  assert(out_is_target != NULL);
-  assert(options != NULL);
+  pony_assert(attribute != NULL);
+  pony_assert(out_is_target != NULL);
+  pony_assert(options != NULL);
 
   if(!strcmp(attribute, OS_FREEBSD_NAME))
   {
diff --git a/src/libponyc/pkg/program.c b/src/libponyc/pkg/program.c
index f92b5f5b5a4..5b9534fc92a 100644
--- a/src/libponyc/pkg/program.c
+++ b/src/libponyc/pkg/program.c
@@ -2,8 +2,8 @@
 #include "package.h"
 #include "../ast/stringtab.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 
 // Per program state.
@@ -21,8 +21,8 @@ typedef struct program_t
 // Append the given text to the program's lib args, handling reallocs.
 static void append_to_args(program_t* program, const char* text)
 {
-  assert(program != NULL);
-  assert(text != NULL);
+  pony_assert(program != NULL);
+  pony_assert(text != NULL);
 
   size_t text_len = strlen(text);
   size_t new_len = program->lib_args_size + text_len + 1; // +1 for terminator
@@ -32,7 +32,7 @@ static void append_to_args(program_t* program, const char* text)
     size_t new_alloc = 2 * new_len; // 2* so there's spare space for next arg
     program->lib_args = (char*)realloc(program->lib_args, new_alloc);
     program->lib_args_alloced = new_alloc;
-    assert(new_len <= program->lib_args_alloced);
+    pony_assert(new_len <= program->lib_args_alloced);
   }
 
   strcat(program->lib_args, text);
@@ -55,7 +55,7 @@ program_t* program_create()
 
 void program_free(program_t* program)
 {
-  assert(program != NULL);
+  pony_assert(program != NULL);
 
   strlist_free(program->libpaths);
   strlist_free(program->libs);
@@ -66,11 +66,11 @@ void program_free(program_t* program)
 
 uint32_t program_assign_pkg_id(ast_t* ast)
 {
-  assert(ast != NULL);
-  assert(ast_id(ast) == TK_PROGRAM);
+  pony_assert(ast != NULL);
+  pony_assert(ast_id(ast) == TK_PROGRAM);
 
   program_t* data = (program_t*)ast_data(ast);
-  assert(data != NULL);
+  pony_assert(data != NULL);
 
   return data->next_package_id++;
 }
@@ -84,7 +84,7 @@ uint32_t program_assign_pkg_id(ast_t* ast)
 static const char* quoted_locator(pass_opt_t* opt, ast_t* use,
   const char* locator)
 {
-  assert(locator != NULL);
+  pony_assert(locator != NULL);
 
   if(strpbrk(locator, INVALID_LOCATOR_CHARS) != NULL)
   {
@@ -117,7 +117,7 @@ bool use_library(ast_t* use, const char* locator, ast_t* name,
 
   ast_t* p = ast_nearest(use, TK_PROGRAM);
   program_t* prog = (program_t*)ast_data(p);
-  assert(prog->lib_args == NULL); // Not yet built args
+  pony_assert(prog->lib_args == NULL); // Not yet built args
 
   if(strlist_find(prog->libs, libname) != NULL) // Ignore duplicate
     return true;
@@ -140,7 +140,7 @@ bool use_path(ast_t* use, const char* locator, ast_t* name,
 
   ast_t* p = ast_nearest(use, TK_PROGRAM);
   program_t* prog = (program_t*)ast_data(p);
-  assert(prog->lib_args == NULL); // Not yet built args
+  pony_assert(prog->lib_args == NULL); // Not yet built args
 
   if(strlist_find(prog->libpaths, libpath) != NULL) // Ignore duplicate
     return true;
@@ -155,16 +155,16 @@ void program_lib_build_args(ast_t* program, pass_opt_t* opt,
   const char* global_preamble, const char* global_postamble,
   const char* lib_premable, const char* lib_postamble)
 {
-  assert(program != NULL);
-  assert(ast_id(program) == TK_PROGRAM);
-  assert(global_preamble != NULL);
-  assert(global_postamble != NULL);
-  assert(lib_premable != NULL);
-  assert(lib_postamble != NULL);
+  pony_assert(program != NULL);
+  pony_assert(ast_id(program) == TK_PROGRAM);
+  pony_assert(global_preamble != NULL);
+  pony_assert(global_postamble != NULL);
+  pony_assert(lib_premable != NULL);
+  pony_assert(lib_postamble != NULL);
 
   program_t* data = (program_t*)ast_data(program);
-  assert(data != NULL);
-  assert(data->lib_args == NULL); // Not yet built args
+  pony_assert(data != NULL);
+  pony_assert(data->lib_args == NULL); // Not yet built args
 
   // Start with an arbitrary amount of space
   data->lib_args_alloced = 256;
@@ -233,12 +233,12 @@ void program_lib_build_args(ast_t* program, pass_opt_t* opt,
 
 const char* program_lib_args(ast_t* program)
 {
-  assert(program != NULL);
-  assert(ast_id(program) == TK_PROGRAM);
+  pony_assert(program != NULL);
+  pony_assert(ast_id(program) == TK_PROGRAM);
 
   program_t* data = (program_t*)ast_data(program);
-  assert(data != NULL);
-  assert(data->lib_args != NULL); // Args have been built
+  pony_assert(data != NULL);
+  pony_assert(data->lib_args != NULL); // Args have been built
 
   return data->lib_args;
 }
diff --git a/src/libponyc/pkg/use.c b/src/libponyc/pkg/use.c
index 7c8782af880..6ba9c1f1f19 100644
--- a/src/libponyc/pkg/use.c
+++ b/src/libponyc/pkg/use.c
@@ -6,8 +6,8 @@
 #include "../pass/pass.h"
 #include "../pass/scope.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 
 /** Use commands are of the form:
@@ -57,9 +57,9 @@ void use_test_handler(use_handler_t handler, bool allow_alias,
 // Find the index of the handler for the given URI
 static int find_handler(pass_opt_t* opt, ast_t* uri, const char** out_locator)
 {
-  assert(uri != NULL);
-  assert(out_locator != NULL);
-  assert(ast_id(uri) == TK_STRING);
+  pony_assert(uri != NULL);
+  pony_assert(out_locator != NULL);
+  pony_assert(ast_id(uri) == TK_STRING);
 
   const char* text = ast_name(uri);
   const char* colon = strchr(text, ':');
@@ -109,9 +109,9 @@ static int find_handler(pass_opt_t* opt, ast_t* uri, const char** out_locator)
 static bool uri_command(pass_opt_t* opt, ast_t* ast, ast_t* uri, ast_t* alias,
   ast_t* guard)
 {
-  assert(uri != NULL);
-  assert(alias != NULL);
-  assert(guard != NULL);
+  pony_assert(uri != NULL);
+  pony_assert(alias != NULL);
+  pony_assert(guard != NULL);
 
   const char* locator;
   int index = find_handler(opt, uri, &locator);
@@ -136,7 +136,7 @@ static bool uri_command(pass_opt_t* opt, ast_t* ast, ast_t* uri, ast_t* alias,
   if(ifdef_cond_normalise(&guard, opt) && !ifdef_cond_eval(guard, opt))
     return true;
 
-  assert(handlers[index].handler != NULL);
+  pony_assert(handlers[index].handler != NULL);
   return handlers[index].handler(ast, locator, alias, opt);
 }
 
@@ -144,7 +144,7 @@ static bool uri_command(pass_opt_t* opt, ast_t* ast, ast_t* uri, ast_t* alias,
 // Handle an ffi command
 static bool ffi_command(pass_opt_t* opt, ast_t* alias)
 {
-  assert(alias != NULL);
+  pony_assert(alias != NULL);
 
   if(ast_id(alias) != TK_NONE)
   {
@@ -158,12 +158,12 @@ static bool ffi_command(pass_opt_t* opt, ast_t* alias)
 
 ast_result_t use_command(ast_t* ast, pass_opt_t* options)
 {
-  assert(ast != NULL);
-  assert(options != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(options != NULL);
 
   AST_GET_CHILDREN(ast, alias, spec, guard);
-  assert(spec != NULL);
-  assert(guard != NULL);
+  pony_assert(spec != NULL);
+  pony_assert(guard != NULL);
 
   switch(ast_id(spec))
   {
@@ -180,7 +180,7 @@ ast_result_t use_command(ast_t* ast, pass_opt_t* options)
     break;
 
   default:
-    assert(0);
+    pony_assert(0);
     return AST_ERROR;
   }
 
diff --git a/src/libponyc/platform/vcvars.c b/src/libponyc/platform/vcvars.c
index 266f270d675..445b14bca78 100644
--- a/src/libponyc/platform/vcvars.c
+++ b/src/libponyc/platform/vcvars.c
@@ -172,8 +172,8 @@ static bool find_kernel32(vcvars_t* vcvars, errors_t* errors)
 
   vcvars->ucrt[0] = '\0';
   strcpy(vcvars->default_libs,
-    "kernel32.lib msvcrt.lib Ws2_32.lib advapi32.lib "
-    "vcruntime.lib legacy_stdio_definitions.lib");
+    "kernel32.lib msvcrt.lib Ws2_32.lib advapi32.lib vcruntime.lib "
+    "legacy_stdio_definitions.lib dbghelp.lib");
 
   strcpy(vcvars->kernel32, sdk.path);
   strcat(vcvars->kernel32, "Lib\\");
diff --git a/src/libponyc/reach/paint.c b/src/libponyc/reach/paint.c
index 32fcbd02477..057a9c5d110 100644
--- a/src/libponyc/reach/paint.c
+++ b/src/libponyc/reach/paint.c
@@ -1,8 +1,8 @@
 #include "paint.h"
 #include "../../libponyrt/ds/hash.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 #include <stdio.h>
 
 /** We use a greedy algorithm that gives a reasonable trade-off between
@@ -127,7 +127,7 @@ typedef struct painter_t
 // Print out a type map, for debugging only
 static void print_typemap(size_t size, uint64_t* map)
 {
-  assert(map != NULL);
+  pony_assert(map != NULL);
 
   for(size_t i = 0; i < size; i++)
   {
@@ -144,7 +144,7 @@ static void print_typemap(size_t size, uint64_t* map)
 // This is not static so compiler doesn't complain about it not being used
 void painter_print(painter_t* painter)
 {
-  assert(painter != NULL);
+  pony_assert(painter != NULL);
 
   printf("Painter typemaps are " __zu " bits\n",
     painter->typemap_size * sizeof(uint64_t) * 8);
@@ -181,8 +181,8 @@ void painter_print(painter_t* painter)
 // Add a method name record
 static name_record_t* add_name(painter_t* painter, const char* name)
 {
-  assert(painter != NULL);
-  assert(name != NULL);
+  pony_assert(painter != NULL);
+  pony_assert(name != NULL);
 
   size_t map_byte_count = painter->typemap_size * sizeof(uint64_t);
 
@@ -201,7 +201,7 @@ static name_record_t* add_name(painter_t* painter, const char* name)
 // Add a colour record
 static colour_record_t* add_colour(painter_t* painter)
 {
-  assert(painter != NULL);
+  pony_assert(painter != NULL);
 
   size_t map_byte_count = painter->typemap_size * sizeof(uint64_t);
 
@@ -232,8 +232,8 @@ static name_record_t* find_name(painter_t* painter, const char* name)
 // are distinct, ie there is no overlap in their bitmaps.
 static bool is_name_compatible(colour_record_t* colour, name_record_t* name)
 {
-  assert(colour != NULL);
-  assert(name != NULL);
+  pony_assert(colour != NULL);
+  pony_assert(name != NULL);
 
   // Check for type bitmap intersection
   for(size_t i = 0; i < name->typemap_size; i++)
@@ -250,8 +250,8 @@ static bool is_name_compatible(colour_record_t* colour, name_record_t* name)
 // Assign the given name to the given colour
 static void assign_name_to_colour(colour_record_t* colour, name_record_t* name)
 {
-  assert(colour != NULL);
-  assert(name != NULL);
+  pony_assert(colour != NULL);
+  pony_assert(name != NULL);
 
   // Union the type bitmaps
   for(size_t i = 0; i < name->typemap_size; i++)
@@ -264,8 +264,8 @@ static void assign_name_to_colour(colour_record_t* colour, name_record_t* name)
 // Step 1
 static void find_names_types_use(painter_t* painter, reach_types_t* types)
 {
-  assert(painter != NULL);
-  assert(types != NULL);
+  pony_assert(painter != NULL);
+  pony_assert(types != NULL);
 
   size_t i = HASHMAP_BEGIN;
   size_t typemap_index = 0;
@@ -274,7 +274,7 @@ static void find_names_types_use(painter_t* painter, reach_types_t* types)
 
   while((t = reach_types_next(types, &i)) != NULL)
   {
-    assert(typemap_index < painter->typemap_size);
+    pony_assert(typemap_index < painter->typemap_size);
     size_t j = HASHMAP_BEGIN;
     reach_method_name_t* n;
 
@@ -343,8 +343,8 @@ static void assign_colours_to_names(painter_t* painter)
 // Step 5
 static void distribute_info(painter_t* painter, reach_types_t* types)
 {
-  assert(painter != NULL);
-  assert(types != NULL);
+  pony_assert(painter != NULL);
+  pony_assert(types != NULL);
 
   size_t i = HASHMAP_BEGIN;
   reach_type_t* t;
@@ -370,7 +370,7 @@ static void distribute_info(painter_t* painter, reach_types_t* types)
         // Store colour assigned to name in reachable types set
         const char* name = m->mangled_name;
         name_record_t* name_rec = find_name(painter, name);
-        assert(name_rec != NULL);
+        pony_assert(name_rec != NULL);
 
         uint32_t colour = name_rec->colour;
         m->vtable_index = colour;
@@ -389,7 +389,7 @@ static void distribute_info(painter_t* painter, reach_types_t* types)
 // Free everything we've allocated
 static void painter_tidy(painter_t* painter)
 {
-  assert(painter != NULL);
+  pony_assert(painter != NULL);
 
   size_t map_byte_count = painter->typemap_size * sizeof(uint64_t);
 
@@ -409,7 +409,7 @@ static void painter_tidy(painter_t* painter)
 
 void paint(reach_types_t* types)
 {
-  assert(types != NULL);
+  pony_assert(types != NULL);
 
   size_t type_count = reach_types_size(types);
 
diff --git a/src/libponyc/reach/reach.c b/src/libponyc/reach/reach.c
index f4494d39d70..dec8d7688b4 100644
--- a/src/libponyc/reach/reach.c
+++ b/src/libponyc/reach/reach.c
@@ -7,9 +7,9 @@
 #include "../type/reify.h"
 #include "../type/subtype.h"
 #include "../../libponyrt/mem/pool.h"
+#include "ponyassert.h"
 #include <stdio.h>
 #include <string.h>
-#include <assert.h>
 
 DEFINE_STACK(reach_method_stack, reach_method_stack_t,
   reach_method_t);
@@ -298,7 +298,7 @@ static void add_rmethod_to_subtypes(reach_t* r, reach_type_t* t,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
 }
 
 static reach_method_t* add_rmethod(reach_t* r, reach_type_t* t,
@@ -498,7 +498,7 @@ static void add_fields(reach_t* r, reach_type_t* t, pass_opt_t* opt)
       {
         ast_t* r_member = lookup(NULL, NULL, t->ast,
           ast_name(ast_child(member)));
-        assert(r_member != NULL);
+        pony_assert(r_member != NULL);
 
         AST_GET_CHILDREN(r_member, name, type, init);
 
@@ -750,7 +750,7 @@ static reach_type_t* add_type(reach_t* r, ast_t* type, pass_opt_t* opt)
       return add_nominal(r, type, opt);
 
     default:
-      assert(0);
+      pony_assert(0);
   }
 
   return NULL;
@@ -930,7 +930,7 @@ static void reachable_expr(reach_t* r, ast_t* ast, pass_opt_t* opt)
     case TK_IF:
     {
       AST_GET_CHILDREN(ast, cond, then_clause, else_clause);
-      assert(ast_id(cond) == TK_SEQ);
+      pony_assert(ast_id(cond) == TK_SEQ);
       cond = ast_child(cond);
 
       ast_t* type = ast_type(ast);
@@ -991,7 +991,7 @@ static void reachable_method(reach_t* r, ast_t* type, const char* name,
     {
       // If the method is a finaliser, don't mark the ref and val versions as
       // reachable.
-      assert(n->cap == TK_BOX);
+      pony_assert(n->cap == TK_BOX);
       return;
     }
 
diff --git a/src/libponyc/type/alias.c b/src/libponyc/type/alias.c
index 0a6ff4f04df..cc54e219a78 100644
--- a/src/libponyc/type/alias.c
+++ b/src/libponyc/type/alias.c
@@ -4,7 +4,7 @@
 #include "cap.h"
 #include "../ast/token.h"
 #include "../ast/astbuild.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static ast_t* alias_single(ast_t* type)
 {
@@ -45,7 +45,7 @@ static ast_t* alias_single(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -106,7 +106,7 @@ static ast_t* recover_single(ast_t* type, token_id rcap)
           break;
 
         default:
-          assert(0);
+          pony_assert(0);
           return NULL;
       }
       break;
@@ -125,7 +125,7 @@ static ast_t* recover_single(ast_t* type, token_id rcap)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return NULL;
   }
 
@@ -226,7 +226,7 @@ ast_t* alias(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -288,7 +288,7 @@ ast_t* consume_type(ast_t* type, token_id cap)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -302,7 +302,7 @@ static ast_t* recover_complex(ast_t* type, token_id cap)
       break;
 
     default:
-      assert(false);
+      pony_assert(false);
       break;
   }
 
@@ -376,7 +376,7 @@ ast_t* recover_type(ast_t* type, token_id cap)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -422,7 +422,7 @@ ast_t* chain_type(ast_t* type, token_id fun_cap, bool recovered_call)
         case TK_CAP_ANY:
           // If the receiver is #any, the call is on a tag method and we can
           // chain as #any.
-          assert(fun_cap == TK_TAG);
+          pony_assert(fun_cap == TK_TAG);
           return ast_dup(type);
 
         default: {}
@@ -430,13 +430,13 @@ ast_t* chain_type(ast_t* type, token_id fun_cap, bool recovered_call)
 
       if(ast_id(eph) == TK_NONE)
       {
-        assert(recovered_call || (fun_cap == TK_TAG));
+        pony_assert(recovered_call || (fun_cap == TK_TAG));
         // If the receiver isn't ephemeral, we recovered the call and the type
         // stays the same.
         return ast_dup(type);
       }
 
-      assert(ast_id(eph) == TK_EPHEMERAL);
+      pony_assert(ast_id(eph) == TK_EPHEMERAL);
 
       // If the call was auto-recovered, no alias can exist outside of the
       // object's isolation boundary.
@@ -474,7 +474,7 @@ ast_t* chain_type(ast_t* type, token_id fun_cap, bool recovered_call)
           break;
 
         default:
-          assert(false);
+          pony_assert(false);
           return NULL;
       }
 
@@ -502,7 +502,7 @@ ast_t* chain_type(ast_t* type, token_id fun_cap, bool recovered_call)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -560,7 +560,7 @@ bool sendable(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -618,6 +618,6 @@ bool immutable_or_opaque(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
diff --git a/src/libponyc/type/assemble.c b/src/libponyc/type/assemble.c
index 7961a29e7bb..629e9e4cf7e 100644
--- a/src/libponyc/type/assemble.c
+++ b/src/libponyc/type/assemble.c
@@ -7,7 +7,7 @@
 #include "../pass/names.h"
 #include "../pass/flatten.h"
 #include "../pass/expr.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static void append_one_to_union(pass_opt_t* opt, ast_t* ast, ast_t* append)
 {
@@ -199,7 +199,7 @@ ast_t* type_sugar(ast_t* from, const char* package, const char* name)
 ast_t* control_type_add_branch(pass_opt_t* opt, ast_t* control_type,
   ast_t* branch)
 {
-  assert(branch != NULL);
+  pony_assert(branch != NULL);
 
   ast_t* branch_type = ast_type(branch);
 
@@ -220,7 +220,7 @@ ast_t* control_type_add_branch(pass_opt_t* opt, ast_t* control_type,
       ast_settype(control_type, old_control);
     }
 
-    assert(ast_id(control_type) == TK_LITERAL);
+    pony_assert(ast_id(control_type) == TK_LITERAL);
 
     // Add a literal branch reference to the new branch
     ast_t* member = ast_from(branch, TK_LITERALBRANCH);
@@ -440,6 +440,6 @@ ast_t* set_cap_and_ephemeral(ast_t* type, token_id cap, token_id ephemeral)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
diff --git a/src/libponyc/type/cap.c b/src/libponyc/type/cap.c
index 52e05a32155..6c211194ec7 100644
--- a/src/libponyc/type/cap.c
+++ b/src/libponyc/type/cap.c
@@ -1,7 +1,7 @@
 #include "cap.h"
 #include "../ast/token.h"
 #include "viewpoint.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 // The resulting eph will always be TK_EPHEMERAL or TK_NONE.
 static void cap_aliasing(token_id* cap, token_id* eph)
@@ -632,7 +632,7 @@ ast_t* cap_fetch(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -701,7 +701,7 @@ token_id cap_dispatch(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return TK_NONE;
 }
 
@@ -847,7 +847,7 @@ bool cap_view_upper(token_id left_cap, token_id left_eph,
     }
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -1018,7 +1018,7 @@ bool cap_view_lower(token_id left_cap, token_id left_eph,
     }
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
diff --git a/src/libponyc/type/compattype.c b/src/libponyc/type/compattype.c
index bf5117d9dd6..2e04529e105 100644
--- a/src/libponyc/type/compattype.c
+++ b/src/libponyc/type/compattype.c
@@ -1,7 +1,7 @@
 #include "compattype.h"
 #include "cap.h"
 #include "viewpoint.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static bool is_nominal_compat_nominal(ast_t* a, ast_t* b)
 {
@@ -200,7 +200,7 @@ static bool is_tuple_compat_x(ast_t* a, ast_t* b)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -229,7 +229,7 @@ static bool is_nominal_compat_x(ast_t* a, ast_t* b)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -258,7 +258,7 @@ static bool is_typeparam_compat_x(ast_t* a, ast_t* b)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -287,7 +287,7 @@ static bool is_arrow_compat_x(ast_t* a, ast_t* b)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -316,6 +316,6 @@ bool is_compat_type(ast_t* a, ast_t* b)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
diff --git a/src/libponyc/type/lookup.c b/src/libponyc/type/lookup.c
index a70abbedd43..1deca2fb7e9 100644
--- a/src/libponyc/type/lookup.c
+++ b/src/libponyc/type/lookup.c
@@ -9,8 +9,8 @@
 #include "../pass/pass.h"
 #include "../pass/expr.h"
 #include "../expr/literal.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 static ast_t* lookup_base(pass_opt_t* opt, ast_t* from, ast_t* orig,
   ast_t* type, const char* name, bool errors);
@@ -18,7 +18,7 @@ static ast_t* lookup_base(pass_opt_t* opt, ast_t* from, ast_t* orig,
 static ast_t* lookup_nominal(pass_opt_t* opt, ast_t* from, ast_t* orig,
   ast_t* type, const char* name, bool errors)
 {
-  assert(ast_id(type) == TK_NOMINAL);
+  pony_assert(ast_id(type) == TK_NOMINAL);
   typecheck_t* t = &opt->check;
 
   ast_t* def = (ast_t*)ast_data(type);
@@ -135,7 +135,7 @@ static ast_t* lookup_nominal(pass_opt_t* opt, ast_t* from, ast_t* orig,
       }
 
       default:
-        assert(0);
+        pony_assert(0);
         return NULL;
     }
 
@@ -375,7 +375,7 @@ static ast_t* lookup_base(pass_opt_t* opt, ast_t* from, ast_t* orig,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
diff --git a/src/libponyc/type/matchtype.c b/src/libponyc/type/matchtype.c
index 37baad846cb..ac6077fa0a7 100644
--- a/src/libponyc/type/matchtype.c
+++ b/src/libponyc/type/matchtype.c
@@ -4,7 +4,7 @@
 #include "subtype.h"
 #include "typeparam.h"
 #include "viewpoint.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static matchtype_t is_x_match_x(ast_t* operand, ast_t* pattern,
   pass_opt_t* opt);
@@ -203,7 +203,7 @@ static matchtype_t is_x_match_tuple(ast_t* operand, ast_t* pattern,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return MATCHTYPE_DENY;
 }
 
@@ -313,7 +313,7 @@ static matchtype_t is_nominal_match_trait(ast_t* operand, ast_t* pattern,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return MATCHTYPE_DENY;
 }
 
@@ -339,7 +339,7 @@ static matchtype_t is_nominal_match_nominal(ast_t* operand, ast_t* pattern,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return MATCHTYPE_DENY;
 }
 
@@ -400,7 +400,7 @@ static matchtype_t is_x_match_nominal(ast_t* operand, ast_t* pattern,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return MATCHTYPE_DENY;
 }
 
@@ -467,7 +467,7 @@ static matchtype_t is_x_match_x(ast_t* operand, ast_t* pattern,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return MATCHTYPE_DENY;
 }
 
diff --git a/src/libponyc/type/reify.c b/src/libponyc/type/reify.c
index e4ca504b2ad..54f7a713fb5 100644
--- a/src/libponyc/type/reify.c
+++ b/src/libponyc/type/reify.c
@@ -4,18 +4,18 @@
 #include "assemble.h"
 #include "alias.h"
 #include "../ast/token.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static void reify_typeparamref(ast_t** astp, ast_t* typeparam, ast_t* typearg)
 {
   ast_t* ast = *astp;
-  assert(ast_id(ast) == TK_TYPEPARAMREF);
+  pony_assert(ast_id(ast) == TK_TYPEPARAMREF);
 
   ast_t* ref_def = (ast_t*)ast_data(ast);
   ast_t* param_def = (ast_t*)ast_data(typeparam);
 
-  assert(ref_def != NULL);
-  assert(param_def != NULL);
+  pony_assert(ref_def != NULL);
+  pony_assert(param_def != NULL);
 
   if(ref_def != param_def)
     return;
@@ -35,7 +35,7 @@ static void reify_typeparamref(ast_t** astp, ast_t* typeparam, ast_t* typearg)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
   }
 
   ast_replace(astp, typearg);
@@ -44,7 +44,7 @@ static void reify_typeparamref(ast_t** astp, ast_t* typeparam, ast_t* typearg)
 static void reify_arrow(ast_t** astp)
 {
   ast_t* ast = *astp;
-  assert(ast_id(ast) == TK_ARROW);
+  pony_assert(ast_id(ast) == TK_ARROW);
   AST_GET_CHILDREN(ast, left, right);
 
   ast_t* r_left = left;
@@ -94,11 +94,11 @@ static void reify_one(ast_t** astp, ast_t* typeparam, ast_t* typearg)
 bool reify_defaults(ast_t* typeparams, ast_t* typeargs, bool errors,
   pass_opt_t* opt)
 {
-  assert(
+  pony_assert(
     (ast_id(typeparams) == TK_TYPEPARAMS) ||
     (ast_id(typeparams) == TK_NONE)
     );
-  assert(
+  pony_assert(
     (ast_id(typeargs) == TK_TYPEARGS) ||
     (ast_id(typeargs) == TK_NONE)
     );
@@ -153,11 +153,11 @@ ast_t* reify(ast_t* ast, ast_t* typeparams, ast_t* typeargs, pass_opt_t* opt,
   bool duplicate)
 {
   (void)opt;
-  assert(
+  pony_assert(
     (ast_id(typeparams) == TK_TYPEPARAMS) ||
     (ast_id(typeparams) == TK_NONE)
     );
-  assert(
+  pony_assert(
     (ast_id(typeargs) == TK_TYPEARGS) ||
     (ast_id(typeargs) == TK_NONE)
     );
@@ -179,8 +179,8 @@ ast_t* reify(ast_t* ast, ast_t* typeparams, ast_t* typeargs, pass_opt_t* opt,
     typearg = ast_sibling(typearg);
   }
 
-  assert(typeparam == NULL);
-  assert(typearg == NULL);
+  pony_assert(typeparam == NULL);
+  pony_assert(typearg == NULL);
   return r_ast;
 }
 
@@ -196,7 +196,7 @@ ast_t* reify_method_def(ast_t* ast, ast_t* typeparams, ast_t* typeargs,
       break;
 
     default:
-      assert(false);
+      pony_assert(false);
   }
 
   // Remove the body AST to avoid duplicating it.
@@ -304,7 +304,7 @@ bool check_constraints(ast_t* orig, ast_t* typeparams, ast_t* typeargs,
     typearg = ast_sibling(typearg);
   }
 
-  assert(typeparam == NULL);
-  assert(typearg == NULL);
+  pony_assert(typeparam == NULL);
+  pony_assert(typearg == NULL);
   return true;
 }
diff --git a/src/libponyc/type/safeto.c b/src/libponyc/type/safeto.c
index 8308f2accc8..20f799fa9ee 100644
--- a/src/libponyc/type/safeto.c
+++ b/src/libponyc/type/safeto.c
@@ -1,7 +1,7 @@
 #include "safeto.h"
 #include "cap.h"
 #include "viewpoint.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static bool safe_field_write(token_id cap, ast_t* type)
 {
@@ -48,7 +48,7 @@ static bool safe_field_write(token_id cap, ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -91,7 +91,7 @@ bool safe_to_write(ast_t* ast, ast_t* type)
     case TK_TUPLE:
     {
       // At this point, we know these will be the same length.
-      assert(ast_id(type) == TK_TUPLETYPE);
+      pony_assert(ast_id(type) == TK_TUPLETYPE);
       ast_t* child = ast_child(ast);
       ast_t* type_child = ast_child(type);
 
@@ -104,7 +104,7 @@ bool safe_to_write(ast_t* ast, ast_t* type)
         type_child = ast_sibling(type_child);
       }
 
-      assert(type_child == NULL);
+      pony_assert(type_child == NULL);
       return true;
     }
 
@@ -119,7 +119,7 @@ bool safe_to_write(ast_t* ast, ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -186,6 +186,6 @@ bool safe_to_autorecover(ast_t* receiver_type, ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
diff --git a/src/libponyc/type/sanitise.c b/src/libponyc/type/sanitise.c
index 76d6f3dea18..91d047d7788 100644
--- a/src/libponyc/type/sanitise.c
+++ b/src/libponyc/type/sanitise.c
@@ -1,19 +1,19 @@
 #include "sanitise.h"
 #include "../ast/astbuild.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 
 // Collect the given type parameter
 static void collect_type_param(ast_t* orig_param, ast_t* params, ast_t* args)
 {
-  assert(orig_param != NULL);
+  pony_assert(orig_param != NULL);
 
   // Get original type parameter info
   AST_GET_CHILDREN(orig_param, id, constraint, deflt);
   const char* name = ast_name(id);
 
   constraint = sanitise_type(constraint);
-  assert(constraint != NULL);
+  pony_assert(constraint != NULL);
 
   // New type parameter has the same constraint as the old one (sanitised)
   if(params != NULL)
@@ -47,7 +47,7 @@ static void collect_type_param(ast_t* orig_param, ast_t* params, ast_t* args)
 
 void collect_type_params(ast_t* ast, ast_t** out_params, ast_t** out_args)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   // Create params and args as TK_NONE, we'll change them if we find any type
   // params
@@ -103,10 +103,10 @@ void collect_type_params(ast_t* ast, ast_t** out_params, ast_t** out_args)
 // Sanitise the given type (sub)AST, which has already been copied
 static void sanitise(ast_t** astp)
 {
-  assert(astp != NULL);
+  pony_assert(astp != NULL);
 
   ast_t* type = *astp;
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   ast_clearflag(*astp, AST_FLAG_PASS_MASK);
 
@@ -114,10 +114,10 @@ static void sanitise(ast_t** astp)
   {
     // We have a type param reference, convert to a nominal
     ast_t* def = (ast_t*)ast_data(type);
-    assert(def != NULL);
+    pony_assert(def != NULL);
 
     const char* name = ast_name(ast_child(def));
-    assert(name != NULL);
+    pony_assert(name != NULL);
 
     REPLACE(astp,
       NODE(TK_NOMINAL,
@@ -138,7 +138,7 @@ static void sanitise(ast_t** astp)
 
 ast_t* sanitise_type(ast_t* type)
 {
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   ast_t* new_type = ast_dup(type);
   sanitise(&new_type);
diff --git a/src/libponyc/type/subtype.c b/src/libponyc/type/subtype.c
index 17535657ef8..089e5e74f77 100644
--- a/src/libponyc/type/subtype.c
+++ b/src/libponyc/type/subtype.c
@@ -8,8 +8,8 @@
 #include "viewpoint.h"
 #include "../ast/astbuild.h"
 #include "../expr/literal.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 
 typedef enum
@@ -180,8 +180,8 @@ static bool is_sub_cap_and_eph(ast_t* sub, ast_t* super, check_cap_t check_cap,
 static bool is_eq_typeargs(ast_t* a, ast_t* b, errorframe_t* errorf,
   pass_opt_t* opt)
 {
-  assert(ast_id(a) == TK_NOMINAL);
-  assert(ast_id(b) == TK_NOMINAL);
+  pony_assert(ast_id(a) == TK_NOMINAL);
+  pony_assert(ast_id(b) == TK_NOMINAL);
 
   // Check typeargs are the same.
   ast_t* a_arg = ast_child(ast_childidx(a, 2));
@@ -375,7 +375,7 @@ static bool is_fun_sub_fun(ast_t* sub, ast_t* super, errorframe_t* errorf,
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -387,7 +387,7 @@ static bool is_fun_sub_fun(ast_t* sub, ast_t* super, errorframe_t* errorf,
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -724,7 +724,7 @@ static bool is_tuple_sub_x(ast_t* sub, ast_t* super, check_cap_t check_cap,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -809,12 +809,12 @@ static bool is_nominal_sub_structural(ast_t* sub, ast_t* super,
     // Reify the method on the subtype.
     ast_t* r_sub_member = reify_method_def(sub_member, sub_typeparams,
       sub_typeargs, opt);
-    assert(r_sub_member != NULL);
+    pony_assert(r_sub_member != NULL);
 
     // Reify the method on the supertype.
     ast_t* r_super_member = reify_method_def(super_member, super_typeparams,
       super_typeargs, opt);
-    assert(r_super_member != NULL);
+    pony_assert(r_super_member != NULL);
 
     // Check the reified methods.
     bool ok = is_fun_sub_fun(r_sub_member, r_super_member, errorf, opt);
@@ -885,7 +885,7 @@ static bool nominal_provides_trait(ast_t* type, ast_t* trait,
   {
     // Reify the child with our typeargs.
     ast_t* r_child = reify(child, typeparams, typeargs, opt, true);
-    assert(r_child != NULL);
+    pony_assert(r_child != NULL);
 
     // Use the cap and ephemerality of the trait.
     ast_t* rr_child = set_cap_and_ephemeral(r_child, tcap, teph);
@@ -1006,7 +1006,7 @@ static bool is_nominal_sub_trait(ast_t* sub, ast_t* super,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -1033,7 +1033,7 @@ static bool is_nominal_sub_nominal(ast_t* sub, ast_t* super,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -1171,7 +1171,7 @@ static bool is_nominal_sub_x(ast_t* sub, ast_t* super, check_cap_t check_cap,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -1285,7 +1285,7 @@ static bool is_typeparam_base_sub_x(ast_t* sub, ast_t* super,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -1511,15 +1511,15 @@ static bool is_arrow_sub_x(ast_t* sub, ast_t* super, check_cap_t check_cap,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
 bool is_x_sub_x(ast_t* sub, ast_t* super, check_cap_t check_cap,
   errorframe_t* errorf, pass_opt_t* opt)
 {
-  assert(sub != NULL);
-  assert(super != NULL);
+  pony_assert(sub != NULL);
+  pony_assert(super != NULL);
 
   if(ast_id(super) == TK_DONTCARETYPE)
     return true;
@@ -1552,7 +1552,7 @@ bool is_x_sub_x(ast_t* sub, ast_t* super, check_cap_t check_cap,
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -1582,7 +1582,7 @@ bool is_eqtype(ast_t* a, ast_t* b, errorframe_t* errorf, pass_opt_t* opt)
 bool is_sub_provides(ast_t* type, ast_t* provides, errorframe_t* errorf,
   pass_opt_t* opt)
 {
-  assert(ast_id(type) == TK_NOMINAL);
+  pony_assert(ast_id(type) == TK_NOMINAL);
   return is_nominal_sub_structural(type, provides, errorf, opt);
 }
 
@@ -1733,7 +1733,7 @@ bool is_constructable(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -1793,7 +1793,7 @@ bool is_concrete(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -1853,7 +1853,7 @@ bool is_known(ast_t* type)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -1912,7 +1912,7 @@ bool is_entity(ast_t* type, token_id entity)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
diff --git a/src/libponyc/type/typeparam.c b/src/libponyc/type/typeparam.c
index 2ff27ce2315..35fc0783f38 100644
--- a/src/libponyc/type/typeparam.c
+++ b/src/libponyc/type/typeparam.c
@@ -2,7 +2,7 @@
 #include "cap.h"
 #include "subtype.h"
 #include "../ast/token.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static token_id cap_union_constraint(token_id a, token_id b)
 {
@@ -333,7 +333,7 @@ static token_id cap_from_constraint(ast_t* type)
   }
 
   // Tuples and arrows can't be used as constraints.
-  assert(0);
+  pony_assert(0);
   return TK_NONE;
 }
 
@@ -433,7 +433,7 @@ static bool apply_cap_to_single(ast_t* type, token_id tcap, token_id teph)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return false;
   }
 
@@ -469,7 +469,7 @@ static bool apply_cap(ast_t* type, token_id tcap, token_id teph)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return false;
 }
 
@@ -497,7 +497,7 @@ static ast_t* constraint_cap(ast_t* typeparamref)
 
 ast_t* typeparam_constraint(ast_t* typeparamref)
 {
-  assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
+  pony_assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
   ast_t* def = (ast_t*)ast_data(typeparamref);
   ast_t* constraint = ast_childidx(def, 1);
   astlist_t* def_list = astlist_push(NULL, def);
@@ -522,13 +522,13 @@ ast_t* typeparam_constraint(ast_t* typeparamref)
 
 ast_t* typeparam_upper(ast_t* typeparamref)
 {
-  assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
+  pony_assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
   return constraint_cap(typeparamref);
 }
 
 ast_t* typeparam_lower(ast_t* typeparamref)
 {
-  assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
+  pony_assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
   ast_t* constraint = typeparam_constraint(typeparamref);
 
   // A constraint must be a final type (primitive, struct, class, actor) in
@@ -541,7 +541,7 @@ ast_t* typeparam_lower(ast_t* typeparamref)
 
 void typeparam_set_cap(ast_t* typeparamref)
 {
-  assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
+  pony_assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
   AST_GET_CHILDREN(typeparamref, id, cap, eph);
   ast_t* constraint = typeparam_constraint(typeparamref);
   token_id tcap = cap_from_constraint(constraint);
diff --git a/src/libponyc/type/viewpoint.c b/src/libponyc/type/viewpoint.c
index fe9b7f30cac..b09d80d5328 100644
--- a/src/libponyc/type/viewpoint.c
+++ b/src/libponyc/type/viewpoint.c
@@ -3,7 +3,7 @@
 #include "assemble.h"
 #include "cap.h"
 #include "../ast/astbuild.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 enum
 {
@@ -66,7 +66,7 @@ ast_t* viewpoint_type(ast_t* l_type, ast_t* r_type)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return NULL;
   }
 
@@ -120,7 +120,7 @@ ast_t* viewpoint_type(ast_t* l_type, ast_t* r_type)
     }
 
     default:
-      assert(0);
+      pony_assert(0);
       return NULL;
   }
 
@@ -151,7 +151,7 @@ ast_t* viewpoint_upper(ast_t* type)
   // upper(s p'->T k p) = isect[k' in s](T (k'->k) eph(s, p', p))
   // eph(s, p', p) = { unalias(p) if p' = ^, forall k in s . k in {iso, trn}
   //                 { p          otherwise
-  assert(ast_id(type) == TK_ARROW);
+  pony_assert(ast_id(type) == TK_ARROW);
   AST_GET_CHILDREN(type, left, right);
   ast_t* r_right = right;
 
@@ -170,7 +170,7 @@ ast_t* viewpoint_upper(ast_t* type)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return NULL;
   }
 
@@ -204,7 +204,7 @@ ast_t* viewpoint_upper(ast_t* type)
     }
 
     default:
-      assert(0);
+      pony_assert(0);
       return NULL;
   }
 
@@ -233,7 +233,7 @@ ast_t* viewpoint_lower(ast_t* type)
   // upper(s p'->T k p) = union[k' in s](T (k'->k) eph(s, p', p))
   // eph(s, p', p) = { unalias(p) if p' = ^, exists k in s . k in {iso, trn}
   //                 { p          otherwise
-  assert(ast_id(type) == TK_ARROW);
+  pony_assert(ast_id(type) == TK_ARROW);
   AST_GET_CHILDREN(type, left, right);
   ast_t* r_right = right;
 
@@ -252,7 +252,7 @@ ast_t* viewpoint_lower(ast_t* type)
       break;
 
     default:
-      assert(0);
+      pony_assert(0);
       return NULL;
   }
 
@@ -286,7 +286,7 @@ ast_t* viewpoint_lower(ast_t* type)
     }
 
     default:
-      assert(0);
+      pony_assert(0);
       return NULL;
   }
 
@@ -366,7 +366,7 @@ static void replace_type(ast_t** astp, ast_t* target, ast_t* with)
       }
 
       default:
-        assert(0);
+        pony_assert(0);
     }
   } else if(ast_id(ast) == TK_ARROW) {
     // Recalculate all arrow types.
@@ -381,7 +381,7 @@ ast_t* viewpoint_replace(ast_t* ast, ast_t* target, ast_t* with)
   // Target is thistype or a typeparamref. With is a type (when replacing
   // `this` in a reified method signature) or a single capability (when
   // typechecking arrow types).
-  assert(
+  pony_assert(
     (ast_id(target) == TK_THISTYPE) ||
     (ast_id(target) == TK_TYPEPARAMREF));
 
@@ -408,7 +408,7 @@ static void replace_typeparam(ast_t* tuple, ast_t* type, ast_t* typeparamref,
 
 ast_t* viewpoint_reifytypeparam(ast_t* type, ast_t* typeparamref)
 {
-  assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
+  pony_assert(ast_id(typeparamref) == TK_TYPEPARAMREF);
   AST_GET_CHILDREN(typeparamref, id, cap, eph);
 
   switch(ast_id(cap))
@@ -472,7 +472,7 @@ ast_t* viewpoint_reifytypeparam(ast_t* type, ast_t* typeparamref)
     default: {}
   }
 
-  assert(0);
+  pony_assert(0);
   return NULL;
 }
 
@@ -497,8 +497,8 @@ ast_t* viewpoint_reifythis(ast_t* type)
 
 bool viewpoint_reifypair(ast_t* a, ast_t* b, ast_t** r_a, ast_t** r_b)
 {
-  assert(ast_id(a) == TK_ARROW);
-  assert(ast_id(b) == TK_ARROW);
+  pony_assert(ast_id(a) == TK_ARROW);
+  pony_assert(ast_id(b) == TK_ARROW);
 
   // Find the first left side that needs reification.
   ast_t* test = a;
diff --git a/src/libponyc/verify/call.c b/src/libponyc/verify/call.c
index 2914d5cd283..4e8c55b9139 100644
--- a/src/libponyc/verify/call.c
+++ b/src/libponyc/verify/call.c
@@ -1,12 +1,12 @@
 #include "call.h"
 #include "../pkg/package.h"
 #include "../type/lookup.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 
 static bool check_partial_function_call(pass_opt_t* opt, ast_t* ast)
 {
-  assert((ast_id(ast) == TK_FUNREF) || (ast_id(ast) == TK_FUNCHAIN) ||
+  pony_assert((ast_id(ast) == TK_FUNREF) || (ast_id(ast) == TK_FUNCHAIN) ||
     (ast_id(ast) == TK_NEWREF));
   AST_GET_CHILDREN(ast, receiver, method);
 
@@ -18,7 +18,7 @@ static bool check_partial_function_call(pass_opt_t* opt, ast_t* ast)
   // Look up the original method definition for this method call.
   ast_t* method_def = lookup(opt, receiver, ast_type(receiver),
     ast_name(method));
-  assert(ast_id(method_def) == TK_FUN || ast_id(method_def) == TK_BE ||
+  pony_assert(ast_id(method_def) == TK_FUN || ast_id(method_def) == TK_BE ||
     ast_id(method_def) == TK_NEW);
 
   token_id can_error = ast_id(ast_childidx(method_def, 5));
@@ -32,7 +32,7 @@ static bool check_partial_function_call(pass_opt_t* opt, ast_t* ast)
 
 static bool check_partial_ffi_call(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_FFICALL);
+  pony_assert(ast_id(ast) == TK_FFICALL);
   AST_GET_CHILDREN(ast, call_name, call_ret_typeargs, args, named_args,
     call_error);
 
@@ -43,7 +43,7 @@ static bool check_partial_ffi_call(pass_opt_t* opt, ast_t* ast)
     if(ast_id(call_error) == TK_QUESTION)
       ast_seterror(ast);
   } else {
-    assert(ast_id(decl) == TK_FFIDECL);
+    pony_assert(ast_id(decl) == TK_FFIDECL);
     AST_GET_CHILDREN(decl, decl_name, decl_ret_typeargs, params, named_params,
       decl_error);
 
@@ -66,7 +66,7 @@ static bool check_partial_ffi_call(pass_opt_t* opt, ast_t* ast)
 
 bool verify_function_call(pass_opt_t* opt, ast_t* ast)
 {
-  assert((ast_id(ast) == TK_FUNREF) || (ast_id(ast) == TK_FUNCHAIN) ||
+  pony_assert((ast_id(ast) == TK_FUNREF) || (ast_id(ast) == TK_FUNCHAIN) ||
     (ast_id(ast) == TK_NEWREF));
 
   ast_inheritflags(ast);
@@ -81,7 +81,7 @@ bool verify_function_call(pass_opt_t* opt, ast_t* ast)
 bool verify_behaviour_call(pass_opt_t* opt, ast_t* ast)
 {
   (void)opt;
-  assert((ast_id(ast) == TK_BEREF) || (ast_id(ast) == TK_BECHAIN) ||
+  pony_assert((ast_id(ast) == TK_BEREF) || (ast_id(ast) == TK_BECHAIN) ||
     (ast_id(ast) == TK_NEWBEREF));
 
   ast_inheritflags(ast);
@@ -92,7 +92,7 @@ bool verify_behaviour_call(pass_opt_t* opt, ast_t* ast)
 
 bool verify_ffi_call(pass_opt_t* opt, ast_t* ast)
 {
-  assert(ast_id(ast) == TK_FFICALL);
+  pony_assert(ast_id(ast) == TK_FFICALL);
 
   if(!package_allow_ffi(&opt->check))
   {
diff --git a/src/libponyc/verify/control.c b/src/libponyc/verify/control.c
index 06479e720af..05c5434f009 100644
--- a/src/libponyc/verify/control.c
+++ b/src/libponyc/verify/control.c
@@ -1,10 +1,10 @@
 #include "control.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 
 bool verify_try(pass_opt_t* opt, ast_t* ast)
 {
-  assert((ast_id(ast) == TK_TRY) || (ast_id(ast) == TK_TRY_NO_CHECK));
+  pony_assert((ast_id(ast) == TK_TRY) || (ast_id(ast) == TK_TRY_NO_CHECK));
   AST_GET_CHILDREN(ast, body, else_clause, then_clause);
 
   // It has to be possible for the left side to result in an error.
diff --git a/src/libponyc/verify/fun.c b/src/libponyc/verify/fun.c
index 38a2c97d13b..7d57f165ead 100644
--- a/src/libponyc/verify/fun.c
+++ b/src/libponyc/verify/fun.c
@@ -1,7 +1,7 @@
 #include "fun.h"
 #include "../type/subtype.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 
 static bool verify_main_create(pass_opt_t* opt, ast_t* ast)
@@ -216,7 +216,7 @@ static bool show_partiality(pass_opt_t* opt, ast_t* ast)
 
 bool verify_fun(pass_opt_t* opt, ast_t* ast)
 {
-  assert((ast_id(ast) == TK_BE) || (ast_id(ast) == TK_FUN) ||
+  pony_assert((ast_id(ast) == TK_BE) || (ast_id(ast) == TK_FUN) ||
     (ast_id(ast) == TK_NEW));
   AST_GET_CHILDREN(ast, cap, id, typeparams, params, type, can_error, body);
 
diff --git a/src/libponyrt/actor/actor.c b/src/libponyrt/actor/actor.c
index 7051ef716a2..ba845ecbdde 100644
--- a/src/libponyrt/actor/actor.c
+++ b/src/libponyrt/actor/actor.c
@@ -6,9 +6,9 @@
 #include "../mem/pool.h"
 #include "../gc/cycle.h"
 #include "../gc/trace.h"
+#include "ponyassert.h"
 #include <string.h>
 #include <stdio.h>
-#include <assert.h>
 #include <dtrace.h>
 
 #ifdef USE_VALGRIND
@@ -173,7 +173,7 @@ bool ponyint_actor_run(pony_ctx_t* ctx, pony_actor_t* actor, size_t batch)
 
   // We didn't hit our app message batch limit. We now believe our queue to be
   // empty, but we may have received further messages.
-  assert(app < batch);
+  pony_assert(app < batch);
   try_gc(ctx, actor);
 
   if(has_flag(actor, FLAG_UNSCHEDULED))
@@ -204,7 +204,7 @@ bool ponyint_actor_run(pony_ctx_t* ctx, pony_actor_t* actor, size_t batch)
 
 void ponyint_actor_destroy(pony_actor_t* actor)
 {
-  assert(has_flag(actor, FLAG_PENDINGDESTROY));
+  pony_assert(has_flag(actor, FLAG_PENDINGDESTROY));
 
   // Make sure the actor being destroyed has finished marking its queue
   // as empty. Otherwise, it may spuriously see that tail and head are not
@@ -284,7 +284,7 @@ void ponyint_actor_setnoblock(bool state)
 
 PONY_API pony_actor_t* pony_create(pony_ctx_t* ctx, pony_type_t* type)
 {
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   DTRACE1(ACTOR_ALLOC, (uintptr_t)ctx->scheduler);
 
@@ -448,6 +448,6 @@ PONY_API void pony_become(pony_ctx_t* ctx, pony_actor_t* actor)
 
 PONY_API void pony_poll(pony_ctx_t* ctx)
 {
-  assert(ctx->current != NULL);
+  pony_assert(ctx->current != NULL);
   ponyint_actor_run(ctx, ctx->current, 1);
 }
diff --git a/src/libponyrt/actor/messageq.c b/src/libponyrt/actor/messageq.c
index 8ffd80910d0..04689f3405b 100644
--- a/src/libponyrt/actor/messageq.c
+++ b/src/libponyrt/actor/messageq.c
@@ -2,8 +2,8 @@
 
 #include "messageq.h"
 #include "../mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 #ifdef USE_VALGRIND
 #include <valgrind/helgrind.h>
@@ -45,7 +45,7 @@ void ponyint_messageq_init(messageq_t* q)
 void ponyint_messageq_destroy(messageq_t* q)
 {
   pony_msg_t* tail = q->tail;
-  assert((((uintptr_t)atomic_load_explicit(&q->head, memory_order_acquire) &
+  pony_assert((((uintptr_t)atomic_load_explicit(&q->head, memory_order_acquire) &
     ~(uintptr_t)1)) == (uintptr_t)tail);
 #ifdef USE_VALGRIND
 #  ifdef NDEBUG
diff --git a/src/libponyrt/asio/event.c b/src/libponyrt/asio/event.c
index 6a061f5ed43..a1a0ef8e655 100644
--- a/src/libponyrt/asio/event.c
+++ b/src/libponyrt/asio/event.c
@@ -2,8 +2,8 @@
 #include "asio.h"
 #include "../actor/actor.h"
 #include "../mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 PONY_API asio_event_t* pony_asio_event_create(pony_actor_t* owner, int fd,
   uint32_t flags, uint64_t nsec, bool noisy)
@@ -43,7 +43,7 @@ PONY_API void pony_asio_event_destroy(asio_event_t* ev)
 {
   if((ev == NULL) || (ev->magic != ev) || (ev->flags != ASIO_DISPOSABLE))
   {
-    assert(0);
+    pony_assert(0);
     return;
   }
 
diff --git a/src/libponyrt/asio/kqueue.c b/src/libponyrt/asio/kqueue.c
index a6adb72a0c4..19f5659ad4f 100644
--- a/src/libponyrt/asio/kqueue.c
+++ b/src/libponyrt/asio/kqueue.c
@@ -4,13 +4,13 @@
 
 #include "../actor/messageq.h"
 #include "../mem/pool.h"
+#include "ponyassert.h"
 #include <sys/event.h>
 #include <string.h>
 #include <stdbool.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <signal.h>
-#include <assert.h>
 
 struct asio_backend_t
 {
@@ -196,7 +196,7 @@ PONY_API void pony_asio_event_subscribe(asio_event_t* ev)
     (ev->flags == ASIO_DISPOSABLE) ||
     (ev->flags == ASIO_DESTROYED))
   {
-    assert(0);
+    pony_assert(0);
     return;
   }
 
@@ -253,7 +253,7 @@ PONY_API void pony_asio_event_setnsec(asio_event_t* ev, uint64_t nsec)
     (ev->flags == ASIO_DISPOSABLE) ||
     (ev->flags == ASIO_DESTROYED))
   {
-    assert(0);
+    pony_assert(0);
     return;
   }
 
@@ -286,7 +286,7 @@ PONY_API void pony_asio_event_unsubscribe(asio_event_t* ev)
     (ev->flags == ASIO_DISPOSABLE) ||
     (ev->flags == ASIO_DESTROYED))
   {
-    assert(0);
+    pony_assert(0);
     return;
   }
 
diff --git a/src/libponyrt/ds/hash.c b/src/libponyrt/ds/hash.c
index ec59a7dbaa6..9423d1571e5 100644
--- a/src/libponyrt/ds/hash.c
+++ b/src/libponyrt/ds/hash.c
@@ -1,7 +1,7 @@
 #include "hash.h"
+#include "ponyassert.h"
 #include <stdlib.h>
 #include <string.h>
-#include <assert.h>
 
 // Minimum HASHMAP size allowed
 #define MIN_HASHMAP_SIZE 8
@@ -97,7 +97,7 @@ static void resize(hashmap_t* map, cmp_fn cmp, alloc_fn alloc,
       (s * sizeof(hashmap_entry_t)), old_item_bitmap);
   }
 
-  assert(map->count == c);
+  pony_assert(map->count == c);
 }
 
 static size_t optimize_item(hashmap_t* map, alloc_fn alloc,
@@ -222,11 +222,11 @@ static void shift_put(hashmap_t* map, void* entry, size_t hash, cmp_fn cmp,
   size_t probe_length = pl;
   size_t oi_probe_length = oi_pl;
 
-  assert(probe_length > oi_probe_length ||
+  pony_assert(probe_length > oi_probe_length ||
     (probe_length == oi_probe_length && probe_length == 0));
 
   while(true) {
-    assert(pos < map->size);
+    pony_assert(pos < map->size);
 
     // need to swap elements
     if(elem == NULL && map->buckets[pos].ptr != NULL)
@@ -307,7 +307,7 @@ void ponyint_hashmap_putindex(hashmap_t* map, void* entry, size_t hash,
   if(map->size == 0)
     ponyint_hashmap_init(map, 4, alloc);
 
-  assert(pos < map->size);
+  pony_assert(pos < map->size);
 
   // if bucket is empty
   if(map->buckets[pos].ptr == NULL)
@@ -350,7 +350,7 @@ void ponyint_hashmap_putindex(hashmap_t* map, void* entry, size_t hash,
 
 static void shift_delete(hashmap_t* map, size_t index)
 {
-  assert(index < map->size);
+  pony_assert(index < map->size);
   size_t pos = index;
   size_t mask = map->size - 1;
   size_t next_pos = (pos + 1) & mask;
@@ -445,7 +445,7 @@ void* ponyint_hashmap_next(size_t* i, size_t count, bitmap_t* item_bitmap,
       index += (ffs_offset - 1);
 
       // no need to check if valid element because item bitmap keeps track of it
-      assert(buckets[index].ptr != NULL);
+      pony_assert(buckets[index].ptr != NULL);
       *i = index;
       return buckets[index].ptr;
     }
diff --git a/src/libponyrt/ds/list.c b/src/libponyrt/ds/list.c
index bdc250ed001..d0e68556095 100644
--- a/src/libponyrt/ds/list.c
+++ b/src/libponyrt/ds/list.c
@@ -1,7 +1,7 @@
 #include "list.h"
 #include "../mem/pool.h"
+#include "ponyassert.h"
 #include <stdlib.h>
-#include <assert.h>
 
 typedef struct list_t
 {
diff --git a/src/libponyrt/ds/stack.c b/src/libponyrt/ds/stack.c
index 7f4d26aaff7..23133af8b53 100644
--- a/src/libponyrt/ds/stack.c
+++ b/src/libponyrt/ds/stack.c
@@ -1,6 +1,6 @@
 #include "stack.h"
 #include "../mem/pool.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static Stack* stack_new(Stack* prev, void* data)
 {
@@ -14,8 +14,8 @@ static Stack* stack_new(Stack* prev, void* data)
 
 Stack* ponyint_stack_pop(Stack* stack, void** data)
 {
-  assert(stack != NULL);
-  assert(data != NULL);
+  pony_assert(stack != NULL);
+  pony_assert(data != NULL);
 
   stack->index--;
   *data = stack->data[stack->index];
diff --git a/src/libponyrt/gc/actormap.c b/src/libponyrt/gc/actormap.c
index 3190afded8d..fe0f89ed3d4 100644
--- a/src/libponyrt/gc/actormap.c
+++ b/src/libponyrt/gc/actormap.c
@@ -5,8 +5,8 @@
 #include "../ds/hash.h"
 #include "../ds/fun.h"
 #include "../mem/pool.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 static size_t actorref_hash(actorref_t* aref)
 {
diff --git a/src/libponyrt/gc/cycle.c b/src/libponyrt/gc/cycle.c
index a95375c849a..41a94287042 100644
--- a/src/libponyrt/gc/cycle.c
+++ b/src/libponyrt/gc/cycle.c
@@ -5,10 +5,10 @@
 #include "../ds/stack.h"
 #include "../ds/hash.h"
 #include "../mem/pool.h"
+#include "ponyassert.h"
 #include <stdio.h>
 #include <string.h>
 #include <inttypes.h>
-#include <assert.h>
 
 typedef struct init_msg_t
 {
@@ -268,7 +268,7 @@ static bool mark_grey(detector_t* d, view_t* view, size_t rc)
   if(view->color == COLOR_GREY)
     return false;
 
-  assert(view->color == COLOR_BLACK);
+  pony_assert(view->color == COLOR_BLACK);
   view->color = COLOR_GREY;
   return true;
 }
@@ -298,7 +298,7 @@ static bool mark_black(view_t* view, size_t rc, int* count)
 {
   if(!view->blocked || (view->actor == NULL))
   {
-    assert(view->color == COLOR_BLACK);
+    pony_assert(view->color == COLOR_BLACK);
     return false;
   }
 
@@ -345,7 +345,7 @@ static bool mark_white(view_t* view, int* count)
   if(view->color != COLOR_GREY)
     return false;
 
-  assert(view->blocked);
+  pony_assert(view->blocked);
 
   if(view->rc > 0)
   {
@@ -354,7 +354,7 @@ static bool mark_white(view_t* view, int* count)
     return false;
   }
 
-  assert(view->perceived == NULL);
+  pony_assert(view->perceived == NULL);
 
   view->color = COLOR_WHITE;
   *count = *count + 1;
@@ -390,8 +390,8 @@ static bool collect_view(perceived_t* per, view_t* view, size_t rc, int* count)
 {
   if(view->color == COLOR_WHITE)
   {
-    assert(view->deferred == false);
-    assert(view->perceived == NULL);
+    pony_assert(view->deferred == false);
+    pony_assert(view->perceived == NULL);
 
     view->perceived = per;
     ponyint_viewmap_put(&per->map, view);
@@ -445,11 +445,11 @@ static void send_conf(pony_ctx_t* ctx, detector_t* d, perceived_t* per)
 
 static bool detect(pony_ctx_t* ctx, detector_t* d, view_t* view)
 {
-  assert(view->perceived == NULL);
+  pony_assert(view->perceived == NULL);
 
   scan_grey(d, view, 0);
   int count = scan_white(view);
-  assert(count >= 0);
+  pony_assert(count >= 0);
 
   if(count == 0)
     return false;
@@ -466,8 +466,8 @@ static bool detect(pony_ctx_t* ctx, detector_t* d, view_t* view)
   int count2 = collect_white(per, view, 0);
 
   (void)count2;
-  assert(count2 == count);
-  assert(ponyint_viewmap_size(&per->map) == (size_t)count);
+  pony_assert(count2 == count);
+  pony_assert(ponyint_viewmap_size(&per->map) == (size_t)count);
 
   send_conf(ctx, d, per);
   return true;
@@ -488,7 +488,7 @@ static void deferred(pony_ctx_t* ctx, detector_t* d)
 
   while((view = ponyint_viewmap_next(&d->deferred, &i)) != NULL)
   {
-    assert(view->deferred == true);
+    pony_assert(view->deferred == true);
     ponyint_viewmap_removeindex(&d->deferred, i);
 
     // always scan again from same index because robin hood hashmap
@@ -543,7 +543,7 @@ static void collect(pony_ctx_t* ctx, detector_t* d, perceived_t* per)
   // mark actors in the cycle as pending destruction
   while((view = ponyint_viewmap_next(&per->map, &i)) != NULL)
   {
-    assert(view->perceived == per);
+    pony_assert(view->perceived == per);
 
     // remove from the deferred set
     if(view->deferred)
@@ -631,7 +631,7 @@ static void unblock(detector_t* d, pony_actor_t* actor)
 
   // we must be in the views, because we must have blocked in order to unblock
   view_t* view = ponyint_viewmap_get(&d->views, &key, &index);
-  assert(view != NULL);
+  pony_assert(view != NULL);
 
   // record that we're unblocked
   view->blocked = false;
@@ -775,7 +775,7 @@ static void check_view(detector_t* d, view_t* view)
 
   scan_grey(d, view, 0);
   int count = scan_white(view);
-  assert(count >= 0);
+  pony_assert(count >= 0);
 
   printf("%p: %s\n", view->actor, count > 0 ? "COLLECTABLE" : "uncollectable");
 }
@@ -880,8 +880,8 @@ void ponyint_cycle_create(pony_ctx_t* ctx, uint32_t min_deferred,
 
 void ponyint_cycle_block(pony_ctx_t* ctx, pony_actor_t* actor, gc_t* gc)
 {
-  assert(ctx->current == actor);
-  assert(&actor->gc == gc);
+  pony_assert(ctx->current == actor);
+  pony_assert(&actor->gc == gc);
 
   block_msg_t* m = (block_msg_t*)pony_alloc_msg(
     POOL_INDEX(sizeof(block_msg_t)), ACTORMSG_BLOCK);
@@ -889,7 +889,7 @@ void ponyint_cycle_block(pony_ctx_t* ctx, pony_actor_t* actor, gc_t* gc)
   m->actor = actor;
   m->rc = ponyint_gc_rc(gc);
   m->delta = ponyint_gc_delta(gc);
-  assert(gc->delta == NULL);
+  pony_assert(gc->delta == NULL);
 
   pony_sendv(ctx, cycle_detector, &m->msg);
 }
diff --git a/src/libponyrt/gc/gc.c b/src/libponyrt/gc/gc.c
index d8bb9e986d1..0d92322781a 100644
--- a/src/libponyrt/gc/gc.c
+++ b/src/libponyrt/gc/gc.c
@@ -2,8 +2,8 @@
 #include "../actor/actor.h"
 #include "../sched/scheduler.h"
 #include "../mem/pagemap.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 #define GC_ACTOR_HEAP_EQUIV 1024
 #define GC_IMMUT_HEAP_EQUIV 1024
@@ -51,7 +51,7 @@ static void recv_local_actor(gc_t* gc)
   if(gc->rc_mark != gc->mark)
   {
     gc->rc_mark = gc->mark;
-    assert(gc->rc > 0);
+    pony_assert(gc->rc > 0);
     gc->rc--;
   }
 }
@@ -63,7 +63,7 @@ static void acquire_local_actor(gc_t* gc)
 
 static void release_local_actor(gc_t* gc)
 {
-  assert(gc->rc > 0);
+  pony_assert(gc->rc > 0);
   gc->rc--;
 }
 
@@ -157,7 +157,7 @@ static void recv_local_object(pony_ctx_t* ctx, void* p, pony_type_t* t,
   size_t index = HASHMAP_UNKNOWN;
   gc_t* gc = ponyint_actor_gc(ctx->current);
   object_t* obj = ponyint_objectmap_getobject(&gc->local, p, &index);
-  assert(obj != NULL);
+  pony_assert(obj != NULL);
 
   if(obj->mark == gc->mark)
     return;
@@ -225,7 +225,7 @@ static void release_local_object(pony_ctx_t* ctx, void* p, pony_type_t* t,
   size_t index = HASHMAP_UNKNOWN;
   gc_t* gc = ponyint_actor_gc(ctx->current);
   object_t* obj = ponyint_objectmap_getobject(&gc->local, p, &index);
-  assert(obj != NULL);
+  pony_assert(obj != NULL);
 
   if(obj->mark == gc->mark)
     return;
@@ -652,7 +652,7 @@ bool ponyint_gc_acquire(gc_t* gc, actorref_t* aref)
 bool ponyint_gc_release(gc_t* gc, actorref_t* aref)
 {
   size_t rc = aref->rc;
-  assert(gc->rc >= rc);
+  pony_assert(gc->rc >= rc);
   gc->rc -= rc;
 
   objectmap_t* map = &aref->map;
@@ -665,7 +665,7 @@ bool ponyint_gc_release(gc_t* gc, actorref_t* aref)
     void* p = obj->address;
     object_t* obj_local = ponyint_objectmap_getobject(&gc->local, p, &index);
 
-    assert(obj_local->rc >= obj->rc);
+    pony_assert(obj_local->rc >= obj->rc);
     obj_local->rc -= obj->rc;
   }
 
@@ -696,7 +696,7 @@ void ponyint_gc_sendacquire(pony_ctx_t* ctx)
     pony_sendp(ctx, aref->actor, ACTORMSG_ACQUIRE, aref);
   }
 
-  assert(ponyint_actormap_size(&ctx->acquire) == 0);
+  pony_assert(ponyint_actormap_size(&ctx->acquire) == 0);
 }
 
 void ponyint_gc_sendrelease(pony_ctx_t* ctx, gc_t* gc)
@@ -715,7 +715,7 @@ void ponyint_gc_sendrelease_manual(pony_ctx_t* ctx)
     pony_sendp(ctx, aref->actor, ACTORMSG_RELEASE, aref);
   }
 
-  assert(ponyint_actormap_size(&ctx->acquire) == 0);
+  pony_assert(ponyint_actormap_size(&ctx->acquire) == 0);
 }
 
 void ponyint_gc_register_final(pony_ctx_t* ctx, void* p, pony_final_fn final)
diff --git a/src/libponyrt/gc/objectmap.c b/src/libponyrt/gc/objectmap.c
index 810f15a16b1..7977a30fee3 100644
--- a/src/libponyrt/gc/objectmap.c
+++ b/src/libponyrt/gc/objectmap.c
@@ -4,7 +4,7 @@
 #include "../ds/fun.h"
 #include "../mem/pool.h"
 #include "../mem/pagemap.h"
-#include <assert.h>
+#include "ponyassert.h"
 
 static size_t object_hash(object_t* obj)
 {
diff --git a/src/libponyrt/gc/serialise.c b/src/libponyrt/gc/serialise.c
index f692a7ce1e1..14b07f719ae 100644
--- a/src/libponyrt/gc/serialise.c
+++ b/src/libponyrt/gc/serialise.c
@@ -5,8 +5,8 @@
 #include "serialise.h"
 #include "../sched/scheduler.h"
 #include "../lang/lang.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 #if defined(PLATFORM_IS_POSIX_BASED)
 #include <dlfcn.h>
@@ -194,7 +194,7 @@ PONY_API size_t pony_serialise_offset(pony_ctx_t* ctx, void* p)
 PONY_API void pony_serialise(pony_ctx_t* ctx, void* p, void* out)
 {
   // This can raise an error.
-  assert(ctx->stack == NULL);
+  pony_assert(ctx->stack == NULL);
   ctx->trace_object = ponyint_serialise_object;
   ctx->trace_actor = ponyint_serialise_actor;
   ctx->serialise_size = 0;
diff --git a/src/libponyrt/gc/trace.c b/src/libponyrt/gc/trace.c
index d6477829380..71ddfbce089 100644
--- a/src/libponyrt/gc/trace.c
+++ b/src/libponyrt/gc/trace.c
@@ -3,12 +3,12 @@
 #include "../sched/scheduler.h"
 #include "../sched/cpu.h"
 #include "../actor/actor.h"
-#include <assert.h>
+#include "ponyassert.h"
 #include <dtrace.h>
 
 PONY_API void pony_gc_send(pony_ctx_t* ctx)
 {
-  assert(ctx->stack == NULL);
+  pony_assert(ctx->stack == NULL);
   ctx->trace_object = ponyint_gc_sendobject;
   ctx->trace_actor = ponyint_gc_sendactor;
 
@@ -17,7 +17,7 @@ PONY_API void pony_gc_send(pony_ctx_t* ctx)
 
 PONY_API void pony_gc_recv(pony_ctx_t* ctx)
 {
-  assert(ctx->stack == NULL);
+  pony_assert(ctx->stack == NULL);
   ctx->trace_object = ponyint_gc_recvobject;
   ctx->trace_actor = ponyint_gc_recvactor;
 
@@ -26,21 +26,21 @@ PONY_API void pony_gc_recv(pony_ctx_t* ctx)
 
 void ponyint_gc_mark(pony_ctx_t* ctx)
 {
-  assert(ctx->stack == NULL);
+  pony_assert(ctx->stack == NULL);
   ctx->trace_object = ponyint_gc_markobject;
   ctx->trace_actor = ponyint_gc_markactor;
 }
 
 PONY_API void pony_gc_acquire(pony_ctx_t* ctx)
 {
-  assert(ctx->stack == NULL);
+  pony_assert(ctx->stack == NULL);
   ctx->trace_object = ponyint_gc_acquireobject;
   ctx->trace_actor = ponyint_gc_acquireactor;
 }
 
 PONY_API void pony_gc_release(pony_ctx_t* ctx)
 {
-  assert(ctx->stack == NULL);
+  pony_assert(ctx->stack == NULL);
   ctx->trace_object = ponyint_gc_releaseobject;
   ctx->trace_actor = ponyint_gc_releaseactor;
 }
diff --git a/src/libponyrt/lang/posix_except.c b/src/libponyrt/lang/posix_except.c
index ac25d2dc479..4afff23334e 100644
--- a/src/libponyrt/lang/posix_except.c
+++ b/src/libponyrt/lang/posix_except.c
@@ -3,9 +3,9 @@
 #ifdef PLATFORM_IS_POSIX_BASED
 
 #include "lsda.h"
+#include "ponyassert.h"
 #include <unwind.h>
 #include <stdlib.h>
-#include <assert.h>
 
 PONY_EXTERN_C_BEGIN
 
diff --git a/src/libponyrt/lang/socket.c b/src/libponyrt/lang/socket.c
index 427b689b082..0f3d6e792bb 100644
--- a/src/libponyrt/lang/socket.c
+++ b/src/libponyrt/lang/socket.c
@@ -6,9 +6,9 @@
 #include "lang.h"
 #include "../asio/asio.h"
 #include "../asio/event.h"
+#include "ponyassert.h"
 #include <stdbool.h>
 #include <string.h>
-#include <assert.h>
 
 #ifdef PLATFORM_IS_WINDOWS
 // Disable warnings about deprecated non-unicode WSA functions.
@@ -428,7 +428,7 @@ static int socket_from_addrinfo(struct addrinfo* p, bool reuse)
 #elif defined(PLATFORM_IS_WINDOWS)
   UINT_PTR skt = WSASocket(p->ai_family, p->ai_socktype, p->ai_protocol, NULL,
     0, WSA_FLAG_OVERLAPPED);
-  assert((skt == INVALID_SOCKET) || ((skt >> 31) == 0));
+  pony_assert((skt == INVALID_SOCKET) || ((skt >> 31) == 0));
   int fd = (int)skt;
 #else
   int fd = socket(p->ai_family, p->ai_socktype, p->ai_protocol);
diff --git a/src/libponyrt/mem/heap.c b/src/libponyrt/mem/heap.c
index 46f4c18e265..5442b6ad60d 100644
--- a/src/libponyrt/mem/heap.c
+++ b/src/libponyrt/mem/heap.c
@@ -1,8 +1,8 @@
 #include "heap.h"
 #include "pagemap.h"
 #include "../ds/fun.h"
+#include "ponyassert.h"
 #include <string.h>
-#include <assert.h>
 
 #include <platform.h>
 #include <dtrace.h>
diff --git a/src/libponyrt/mem/pool.c b/src/libponyrt/mem/pool.c
index eba0e055734..aa2b5f393b9 100644
--- a/src/libponyrt/mem/pool.c
+++ b/src/libponyrt/mem/pool.c
@@ -4,12 +4,12 @@
 #include "alloc.h"
 #include "../ds/fun.h"
 #include "../sched/cpu.h"
+#include "ponyassert.h"
 #include <stdint.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <assert.h>
 
 #include <platform.h>
 #include <pony/detail/atomics.h>
@@ -269,7 +269,7 @@ static void track_alloc(void* p, size_t size)
 static void track_free(void* p, size_t size)
 {
   track_init();
-  assert(!track.internal);
+  pony_assert(!track.internal);
 
   track.internal = true;
 
@@ -284,7 +284,7 @@ static void track_free(void* p, size_t size)
 static void track_push(pool_item_t* p, size_t length, size_t size)
 {
   track_init();
-  assert(!track.internal);
+  pony_assert(!track.internal);
 
   track.internal = true;
   uint64_t tsc = ponyint_cpu_tick();
@@ -309,7 +309,7 @@ static void track_push(pool_item_t* p, size_t length, size_t size)
 static void track_pull(pool_item_t* p, size_t length, size_t size)
 {
   track_init();
-  assert(!track.internal);
+  pony_assert(!track.internal);
 
   track.internal = true;
   uint64_t tsc = ponyint_cpu_tick();
@@ -466,7 +466,7 @@ static void pool_push(pool_local_t* thread, pool_global_t* global)
   thread->pool = NULL;
   thread->length = 0;
 
-  assert(p->length == global->count);
+  pony_assert(p->length == global->count);
   TRACK_PUSH((pool_item_t*)p, p->length, global->size);
 
   size_t my_ticket = atomic_fetch_add_explicit(&global->ticket, 1,
@@ -533,7 +533,7 @@ static pool_item_t* pool_pull(pool_local_t* thread, pool_global_t* global)
 
   pool_item_t* p = (pool_item_t*)top;
 
-  assert(top->length == global->count);
+  pony_assert(top->length == global->count);
   TRACK_PULL(p, top->length, global->size);
 
   thread->pool = p->next;
@@ -616,7 +616,7 @@ void ponyint_pool_free(size_t index, void* p)
 #endif
 
   TRACK_FREE(p, POOL_MIN << index);
-  assert(index < POOL_COUNT);
+  pony_assert(index < POOL_COUNT);
 
   pool_local_t* thread = &pool_local[index];
   pool_global_t* global = &pool_global[index];
diff --git a/src/libponyrt/platform/ponyassert.c b/src/libponyrt/platform/ponyassert.c
new file mode 100644
index 00000000000..d0f31db461c
--- /dev/null
+++ b/src/libponyrt/platform/ponyassert.c
@@ -0,0 +1,142 @@
+#define PONY_WANT_ATOMIC_DEFS
+
+#include "ponyassert.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#ifdef PLATFORM_IS_POSIX_BASED
+#  include <execinfo.h>
+#  include <unistd.h>
+#else
+#  include <Windows.h>
+#  include <DbgHelp.h>
+#endif
+
+#include <pony/detail/atomics.h>
+
+static atomic_flag assert_guard = ATOMIC_FLAG_INIT;
+
+#ifdef PLATFORM_IS_POSIX_BASED
+
+void ponyint_assert_fail(const char* expr, const char* file, size_t line,
+  const char* func)
+{
+  while(atomic_flag_test_and_set_explicit(&assert_guard, memory_order_acq_rel))
+  {
+    // If the guard is already set, an assertion fired in another thread. The
+    // things here aren't thread safe, so we just start an infinite loop.
+    struct timespec ts = {1, 0};
+    nanosleep(&ts, NULL);
+  }
+
+  fprintf(stderr, "%s:" __zu ": %s: Assertion `%s` failed.\n\n", file, line,
+    func, expr);
+
+  void* addrs[256];
+  int depth = backtrace(addrs, 256);
+  char** strings = backtrace_symbols(addrs, depth);
+
+  fputs("Backtrace:\n", stderr);
+
+  for(int i = 0; i < depth; i++)
+    printf("  %s\n", strings[i]);
+
+  free(strings);
+
+  if(strcmp(PONY_BUILD_CONFIG, "release") == 0)
+  {
+    fputs("This is an optimised version of ponyc: the backtrace may be "
+      "imprecise or incorrect.\nUse a debug version to get more meaningful "
+      "information.\n", stderr);
+  }
+
+  fflush(stderr);
+  abort();
+}
+
+#elif defined(PLATFORM_IS_WINDOWS)
+
+void ponyint_assert_fail(const char* expr, const char* file, size_t line,
+  const char* func)
+{
+  while(atomic_flag_test_and_set_explicit(&assert_guard, memory_order_acq_rel))
+  {
+    // If the guard is already set, an assertion fired in another thread. The
+    // things here aren't thread safe, so we just start an infinite loop.
+    Sleep(1);
+  }
+
+  fprintf(stderr, "%s:" __zu ": %s: Assertion `%s` failed.\n\n", file, line,
+    func, expr);
+
+  HANDLE process = GetCurrentProcess();
+  HANDLE thread = GetCurrentThread();
+
+  CONTEXT context;
+  memset(&context, 0, sizeof(context));
+  context.ContextFlags = CONTEXT_ALL;
+  RtlCaptureContext(&context);
+  SymInitialize(process, NULL, true);
+
+  STACKFRAME64 frame;
+  memset(&frame, 0, sizeof(frame));
+  frame.AddrPC.Mode = AddrModeFlat;
+  frame.AddrStack.Mode = AddrModeFlat;
+  frame.AddrFrame.Mode = AddrModeFlat;
+
+#  ifdef _M_IX86
+  frame.AddrPC.Offset = context.Eip;
+  frame.AddrStack.Offset = context.Esp;
+  frame.AddrFrame.Offset = context.Ebp;
+  DWORD machine = IMAGE_FILE_MACHINE_I386;
+#  elif defined(_M_X64)
+  frame.AddrPC.Offset = context.Rip;
+  frame.AddrStack.Offset = context.Rsp;
+  frame.AddrFrame.Offset = context.Rbp;
+  DWORD machine = IMAGE_FILE_MACHINE_AMD64;
+#  endif
+
+  fputs("Backtrace:\n", stderr);
+
+  while(true)
+  {
+    SetLastError(0);
+    if(!StackWalk64(machine, process, thread, &frame, &context, 0,
+      SymFunctionTableAccess64, SymGetModuleBase64, 0))
+      break;
+
+    DWORD64 addr = frame.AddrFrame.Offset;
+    if(addr == 0)
+      break;
+
+    union
+    {
+      SYMBOL_INFO sym;
+      BYTE buffer[sizeof(SYMBOL_INFO) + MAX_SYM_NAME];
+    } sym_buf;
+    PSYMBOL_INFO symbol = &sym_buf.sym;
+    symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
+    symbol->MaxNameLen = MAX_SYM_NAME;
+
+    if(SymFromAddr(process, frame.AddrPC.Offset, NULL, symbol))
+    {
+      fprintf(stderr, "  (%s) [%p]\n", symbol->Name,
+        (void*)frame.AddrPC.Offset);
+    } else {
+      fprintf(stderr, "  () [%p]\n", (void*)frame.AddrPC.Offset);
+    }
+  }
+
+  if(strcmp(PONY_BUILD_CONFIG, "release") == 0)
+  {
+    fputs("This is an optimised version of ponyc: the backtrace may be "
+      "imprecise or incorrect.\nUse a debug version to get more meaningful "
+      "information.\n", stderr);
+  }
+
+  SymCleanup(process);
+  fflush(stderr);
+  abort();
+}
+
+#endif
diff --git a/src/libponyrt/sched/scheduler.c b/src/libponyrt/sched/scheduler.c
index f4cf4a31916..fb8e5f57e17 100644
--- a/src/libponyrt/sched/scheduler.c
+++ b/src/libponyrt/sched/scheduler.c
@@ -7,10 +7,10 @@
 #include "../gc/cycle.h"
 #include "../asio/asio.h"
 #include "../mem/pool.h"
+#include "ponyassert.h"
 #include <dtrace.h>
 #include <string.h>
 #include <stdio.h>
-#include <assert.h>
 
 #define SCHED_BATCH 100
 
@@ -277,7 +277,7 @@ static void run(scheduler_t* sched)
       if(actor == NULL)
       {
         // Termination.
-        assert(pop(sched) == NULL);
+        pony_assert(pop(sched) == NULL);
         return;
       }
       DTRACE2(ACTOR_SCHEDULED, (uintptr_t)sched, (uintptr_t)actor);
diff --git a/test/libponyc/lexint.cc b/test/libponyc/lexint.cc
index 270b99a11d4..07151ad4813 100644
--- a/test/libponyc/lexint.cc
+++ b/test/libponyc/lexint.cc
@@ -5,6 +5,7 @@
 #include <ast/lexint.h>
 
 #include "util.h"
+#include "ponyassert.h"
 
 
 class LexIntTest : public testing::Test
@@ -13,7 +14,7 @@ class LexIntTest : public testing::Test
 
 static lexint_t* lexint(lexint_t* i, uint64_t high, uint64_t low)
 {
-  assert(i != NULL);
+  pony_assert(i != NULL);
   i->low = low;
   i->high = high;
   return i;
diff --git a/test/libponyc/matchtype.cc b/test/libponyc/matchtype.cc
index 7d2ad9798af..9505823d263 100644
--- a/test/libponyc/matchtype.cc
+++ b/test/libponyc/matchtype.cc
@@ -3,6 +3,7 @@
 #include <type/matchtype.h>
 #include <ast/astbuild.h>
 #include "util.h"
+#include "ponyassert.h"
 
 #define TEST_COMPILE(src) DO(test_compile(src, "expr"))
 
@@ -343,8 +344,8 @@ TEST_F(MatchTypeTest, Tuples)
   // t1t2 instead.
   ast_t* t1t2 = type_of("t1t2");
   AST_GET_CHILDREN(t1t2, elem1, elem2);
-  assert(ast_id(elem1) == TK_NOMINAL);
-  assert(ast_id(elem2) == TK_NOMINAL);
+  pony_assert(ast_id(elem1) == TK_NOMINAL);
+  pony_assert(ast_id(elem2) == TK_NOMINAL);
 
   REPLACE(&elem2, NODE(TK_DONTCARETYPE));
 
diff --git a/test/libponyc/paint.cc b/test/libponyc/paint.cc
index d713500b260..e9dc18d0569 100644
--- a/test/libponyc/paint.cc
+++ b/test/libponyc/paint.cc
@@ -6,6 +6,7 @@
 #include <../libponyrt/mem/pool.h>
 
 #include "util.h"
+#include "ponyassert.h"
 
 class PaintTest: public testing::Test
 {
@@ -91,7 +92,7 @@ class PaintTest: public testing::Test
       m2.name = n->name;
       reach_method_t* method = reach_methods_get(&n->r_methods, &m2, &index);
 
-      assert(method != NULL);
+      pony_assert(method != NULL);
 
       if(method->vtable_index > max_colour)
         max_colour = method->vtable_index;
diff --git a/test/libponyc/util.cc b/test/libponyc/util.cc
index a6a324ceb00..4db2d034dd2 100644
--- a/test/libponyc/util.cc
+++ b/test/libponyc/util.cc
@@ -10,11 +10,11 @@
 #include <codegen/genjit.h>
 #include <../libponyrt/pony.h>
 #include <../libponyrt/mem/pool.h>
+#include <ponyassert.h>
 
 #include "util.h"
 #include <string.h>
 #include <string>
-#include <assert.h>
 
 using std::string;
 
@@ -108,8 +108,8 @@ static const char* _builtin =
 // Check whether the 2 given ASTs are identical
 static bool compare_asts(ast_t* expected, ast_t* actual, errors_t *errors)
 {
-  assert(expected != NULL);
-  assert(actual != NULL);
+  pony_assert(expected != NULL);
+  pony_assert(actual != NULL);
 
   token_id expected_id = ast_id(expected);
   token_id actual_id = ast_id(actual);
@@ -349,26 +349,26 @@ void PassTest::test_equiv(const char* actual_src, const char* actual_pass,
 
 ast_t* PassTest::type_of(const char* name)
 {
-  assert(name != NULL);
-  assert(program != NULL);
+  pony_assert(name != NULL);
+  pony_assert(program != NULL);
   return type_of_within(program, name);
 }
 
 
 ast_t* PassTest::numeric_literal(uint64_t num)
 {
-  assert(program != NULL);
+  pony_assert(program != NULL);
   return numeric_literal_within(program, num);
 }
 
 
 ast_t* PassTest::lookup_in(ast_t* ast, const char* name)
 {
-  assert(ast != NULL);
-  assert(name != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(name != NULL);
 
   symtab_t* symtab = ast_get_symtab(ast);
-  assert(symtab != NULL);
+  pony_assert(symtab != NULL);
 
   return symtab_find(symtab, stringtab(name), NULL);
 }
@@ -376,18 +376,18 @@ ast_t* PassTest::lookup_in(ast_t* ast, const char* name)
 
 ast_t* PassTest::lookup_type(const char* name)
 {
-  assert(package != NULL);
+  pony_assert(package != NULL);
   return lookup_in(package, name);
 }
 
 
 ast_t* PassTest::lookup_member(const char* type_name, const char* member_name)
 {
-  assert(type_name != NULL);
-  assert(member_name != NULL);
+  pony_assert(type_name != NULL);
+  pony_assert(member_name != NULL);
 
   ast_t* type = lookup_type(type_name);
-  assert(type != NULL);
+  pony_assert(type != NULL);
 
   return lookup_in(type, member_name);
 }
@@ -395,7 +395,7 @@ ast_t* PassTest::lookup_member(const char* type_name, const char* member_name)
 
 bool PassTest::run_program(int* exit_code)
 {
-  assert(compile != NULL);
+  pony_assert(compile != NULL);
 
   pony_exitcode(0);
   jit_symbol_t symbols[] = {{"__DescTable", &__DescTable},
@@ -497,8 +497,8 @@ void PassTest::build_package(const char* pass, const char* src,
 
 ast_t* PassTest::type_of_within(ast_t* ast, const char* name)
 {
-  assert(ast != NULL);
-  assert(name != NULL);
+  pony_assert(ast != NULL);
+  pony_assert(name != NULL);
 
   // Is this node the definition we're looking for?
   switch(ast_id(ast))
@@ -536,7 +536,7 @@ ast_t* PassTest::type_of_within(ast_t* ast, const char* name)
 
 ast_t* PassTest::numeric_literal_within(ast_t* ast, uint64_t num)
 {
-  assert(ast != NULL);
+  pony_assert(ast != NULL);
 
   // Is this node the definition we're looking for?
   if (ast_id(ast) == TK_INT && lexint_cmp64(ast_int(ast), num) == 0)
diff --git a/wscript b/wscript
index d226f63f898..f14625bc0fd 100644
--- a/wscript
+++ b/wscript
@@ -74,7 +74,8 @@ def configure(ctx):
         ctx.env.PONYC_EXTRA_LIBS = [
             'kernel32', 'user32', 'gdi32', 'winspool', 'comdlg32',
             'advapi32', 'shell32', 'ole32', 'oleaut32', 'uuid',
-            'odbc32', 'odbccp32', 'vcruntime', 'ucrt', 'Ws2_32'
+            'odbc32', 'odbccp32', 'vcruntime', 'ucrt', 'Ws2_32',
+            'dbghelp'
         ]
 
         ctx.env.MSVC_VERSIONS = ['msvc ' + MSVC_VERSION + '.0']
@@ -240,7 +241,8 @@ def build(ctx):
         features = 'c cxx cxxstlib seq',
         target   = 'libponyrt',
         source   = ctx.path.ant_glob('src/libponyrt/**/*.c'),
-        includes = [ 'src/common', 'src/libponyrt' ] + sslIncludes
+        includes = [ 'src/common', 'src/libponyrt' ] + sslIncludes,
+        defines  = [ 'PONY_NO_ASSERT' ]
     )
 
     # ponyc