diff --git a/src/celengine/body.cpp b/src/celengine/body.cpp
index e328db099c..29dd42ccd0 100644
--- a/src/celengine/body.cpp
+++ b/src/celengine/body.cpp
@@ -10,6 +10,7 @@
 #include "body.h"
 
 #include <algorithm>
+#include <cassert>
 #include <cmath>
 #include <utility>
 
diff --git a/src/celengine/category.cpp b/src/celengine/category.cpp
index 4b6f10771b..5fded6f91a 100644
--- a/src/celengine/category.cpp
+++ b/src/celengine/category.cpp
@@ -1,6 +1,7 @@
 #include "category.h"
 
 #include <algorithm>
+#include <cassert>
 #include <initializer_list>
 #include <utility>
 
diff --git a/src/celengine/glmarker.cpp b/src/celengine/glmarker.cpp
index 82e0933aa0..985ea12e8a 100644
--- a/src/celengine/glmarker.cpp
+++ b/src/celengine/glmarker.cpp
@@ -9,6 +9,7 @@
 // of the License, or (at your option) any later version.
 
 #include <array>
+#include <cassert>
 #include <cstddef>
 
 #include <celcompat/numbers.h>
diff --git a/src/celengine/rendcontext.cpp b/src/celengine/rendcontext.cpp
index 4c1578033f..80b2951bc7 100644
--- a/src/celengine/rendcontext.cpp
+++ b/src/celengine/rendcontext.cpp
@@ -9,6 +9,7 @@
 // of the License, or (at your option) any later version.
 
 #include <algorithm>
+#include <cassert>
 #include <cstddef>
 
 #include <celrender/gl/vertexobject.h>
diff --git a/src/celengine/texture.cpp b/src/celengine/texture.cpp
index 7742e14b40..d812fbb604 100644
--- a/src/celengine/texture.cpp
+++ b/src/celengine/texture.cpp
@@ -342,7 +342,7 @@ cubeVector(int face, float s, float t)
         v = Eigen::Vector3f(-s, -t, -1.0f);
         break;
     default:
-        // assert(false);
+        assert(false);
         break;
     }
 
diff --git a/src/celestia/celestiacore.h b/src/celestia/celestiacore.h
index 775b69751b..817090ead0 100644
--- a/src/celestia/celestiacore.h
+++ b/src/celestia/celestiacore.h
@@ -10,6 +10,7 @@
 #pragma once
 
 #include <array>
+#include <cassert>
 #include <fstream>
 #include <locale>
 #include <string>
diff --git a/src/celscript/lua/celx_internal.h b/src/celscript/lua/celx_internal.h
index 0ee7924bfe..b3c8d8ac69 100644
--- a/src/celscript/lua/celx_internal.h
+++ b/src/celscript/lua/celx_internal.h
@@ -12,6 +12,7 @@
 
 #pragma once
 
+#include <cassert>
 #include <iterator>
 #include <memory>
 #include <map>
diff --git a/src/celscript/lua/celx_object.cpp b/src/celscript/lua/celx_object.cpp
index 2434e9c672..27b1a29be2 100644
--- a/src/celscript/lua/celx_object.cpp
+++ b/src/celscript/lua/celx_object.cpp
@@ -9,6 +9,7 @@
 // as published by the Free Software Foundation; either version 2
 // of the License, or (at your option) any later version.
 
+#include <cassert>
 #include <cstring>
 #include <iostream>
 
diff --git a/src/celscript/lua/celx_phase.cpp b/src/celscript/lua/celx_phase.cpp
index 7a19e44498..880b959f4f 100644
--- a/src/celscript/lua/celx_phase.cpp
+++ b/src/celscript/lua/celx_phase.cpp
@@ -9,7 +9,7 @@
 // as published by the Free Software Foundation; either version 2
 // of the License, or (at your option) any later version.
 
-#include <assert.h>
+#include <cassert>
 #include "celx.h"
 #include "celx_internal.h"
 #include "celx_phase.h"
diff --git a/src/celutil/indexlist.h b/src/celutil/indexlist.h
index 8bf5197487..454fce9e03 100644
--- a/src/celutil/indexlist.h
+++ b/src/celutil/indexlist.h
@@ -7,7 +7,9 @@
 // as published by the Free Software Foundation; either version 2
 // of the License, or (at your option) any later version.
 
+#include <cassert>
 #include <limits>
+#include <type_traits>
 #include <vector>
 
 namespace celestia::util