diff --git a/Makefile b/Makefile
index bb303091..a44f110e 100644
--- a/Makefile
+++ b/Makefile
@@ -787,7 +787,8 @@ $(LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS) $(LIBWASI_EMULATED_PROCESS_CLOCKS_SO_OBJ
 $(LIBWASI_EMULATED_PTHREAD_OBJS) $(LIBWASI_EMULATED_PTHREAD_SO_OBJS): CFLAGS += \
     -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/include \
     -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/internal \
-    -I$(LIBC_TOP_HALF_MUSL_DIR)/arch/wasm32
+    -I$(LIBC_TOP_HALF_MUSL_DIR)/arch/wasm32 \
+    -D_WASI_EMULATED_PTHREAD
 
 # emmalloc uses a lot of pointer type-punning, which is UB under strict aliasing,
 # and this was found to have real miscompilations in wasi-libc#421.
diff --git a/expected/wasm32-wasip1/predefined-macros.txt b/expected/wasm32-wasip1/predefined-macros.txt
index 5d56b996..dcce9410 100644
--- a/expected/wasm32-wasip1/predefined-macros.txt
+++ b/expected/wasm32-wasip1/predefined-macros.txt
@@ -3347,7 +3347,12 @@
 #define preadv64 preadv
 #define pthread_cleanup_pop(r) _pthread_cleanup_pop(&__cb, (r)); } while(0)
 #define pthread_cleanup_push(f,x) do { struct __ptcb __cb; _pthread_cleanup_push(&__cb, f, x);
+#define pthread_create(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_detach(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
 #define pthread_equal(x,y) ((x)==(y))
+#define pthread_join(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_timedjoin_np(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_tryjoin_np(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
 #define pwrite64 pwrite
 #define pwritev64 pwritev
 #define readdir64 readdir
diff --git a/expected/wasm32-wasip2/predefined-macros.txt b/expected/wasm32-wasip2/predefined-macros.txt
index bb766d77..d8229353 100644
--- a/expected/wasm32-wasip2/predefined-macros.txt
+++ b/expected/wasm32-wasip2/predefined-macros.txt
@@ -3502,7 +3502,12 @@
 #define preadv64 preadv
 #define pthread_cleanup_pop(r) _pthread_cleanup_pop(&__cb, (r)); } while(0)
 #define pthread_cleanup_push(f,x) do { struct __ptcb __cb; _pthread_cleanup_push(&__cb, f, x);
+#define pthread_create(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_detach(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
 #define pthread_equal(x,y) ((x)==(y))
+#define pthread_join(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_timedjoin_np(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_tryjoin_np(...) _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
 #define pwrite64 pwrite
 #define pwritev64 pwritev
 #define readdir64 readdir
diff --git a/libc-top-half/musl/include/pthread.h b/libc-top-half/musl/include/pthread.h
index 2c35d0b5..3a5566fe 100644
--- a/libc-top-half/musl/include/pthread.h
+++ b/libc-top-half/musl/include/pthread.h
@@ -77,12 +77,29 @@ extern "C" {
 #define PTHREAD_NULL ((pthread_t)0)
 
 
+#ifdef __wasilibc_unmodified_upstream
 int pthread_create(pthread_t *__restrict, const pthread_attr_t *__restrict, void *(*)(void *), void *__restrict);
 int pthread_detach(pthread_t);
-#ifdef __wasilibc_unmodified_upstream
 _Noreturn void pthread_exit(void *);
-#endif
 int pthread_join(pthread_t, void **);
+#else
+#if defined(_WASI_EMULATED_PTHREAD) || defined(_REENTRANT)
+int pthread_create(pthread_t *__restrict, const pthread_attr_t *__restrict, void *(*)(void *), void *__restrict);
+int pthread_detach(pthread_t);
+int pthread_join(pthread_t, void **);
+#else
+#include <assert.h>
+#define pthread_create(...) _Static_assert(0, "This mode of WASI does not have threads enabled; \
+to enable stub functions which always fail, \
+compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_detach(...) _Static_assert(0, "This mode of WASI does not have threads enabled; \
+to enable stub functions which always fail, \
+compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_join(...) _Static_assert(0, "This mode of WASI does not have threads enabled; \
+to enable stub functions which always fail, \
+compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#endif
+#endif
 
 #ifdef __GNUC__
 __attribute__((const))
@@ -232,8 +249,17 @@ int pthread_setname_np(pthread_t, const char *);
 int pthread_getname_np(pthread_t, char *, size_t);
 int pthread_getattr_default_np(pthread_attr_t *);
 int pthread_setattr_default_np(const pthread_attr_t *);
+#if defined(__wasilibc_unmodified_upstream) || defined(_WASI_EMULATED_PTHREAD) || defined(_REENTRANT)
 int pthread_tryjoin_np(pthread_t, void **);
 int pthread_timedjoin_np(pthread_t, void **, const struct timespec *);
+#else
+#define pthread_tryjoin_np(...) _Static_assert(0, "This mode of WASI does not have threads enabled; \
+to enable stub functions which always fail, \
+compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#define pthread_timedjoin_np(...) _Static_assert(0, "This mode of WASI does not have threads enabled; \
+to enable stub functions which always fail, \
+compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread")
+#endif
 #endif
 
 #if _REDIR_TIME64