diff --git a/src/glcanvas.cpp b/src/glcanvas.cpp
index ec1ca4f..6ebf5a9 100644
--- a/src/glcanvas.cpp
+++ b/src/glcanvas.cpp
@@ -18,6 +18,7 @@
 #include <nanogui/theme.h>
 #include <nanogui/opengl.h>
 #include <nanogui/serializer/core.h>
+#include <cassert>
 
 NAMESPACE_BEGIN(nanogui)
 
diff --git a/src/imageview.cpp b/src/imageview.cpp
index 80cdf9b..f0ebbaf 100644
--- a/src/imageview.cpp
+++ b/src/imageview.cpp
@@ -15,6 +15,7 @@
 #include <nanogui/window.h>
 #include <nanogui/screen.h>
 #include <nanogui/theme.h>
+#include <cassert>
 #include <cmath>
 
 NAMESPACE_BEGIN(nanogui)
diff --git a/src/stackedwidget.cpp b/src/stackedwidget.cpp
index 0b56b31..16b07cc 100644
--- a/src/stackedwidget.cpp
+++ b/src/stackedwidget.cpp
@@ -13,6 +13,7 @@
 */
 
 #include <nanogui/stackedwidget.h>
+#include <cassert>
 
 NAMESPACE_BEGIN(nanogui)
 
diff --git a/src/tabheader.cpp b/src/tabheader.cpp
index e3a24ff..86e1493 100644
--- a/src/tabheader.cpp
+++ b/src/tabheader.cpp
@@ -14,6 +14,7 @@
 #include <nanogui/tabheader.h>
 #include <nanogui/theme.h>
 #include <nanogui/opengl.h>
+#include <cassert>
 #include <numeric>
 
 NAMESPACE_BEGIN(nanogui)
diff --git a/src/tabwidget.cpp b/src/tabwidget.cpp
index e01b5c3..0a3f76c 100644
--- a/src/tabwidget.cpp
+++ b/src/tabwidget.cpp
@@ -19,6 +19,7 @@
 #include <nanogui/opengl.h>
 #include <nanogui/window.h>
 #include <nanogui/screen.h>
+#include <cassert>
 #include <algorithm>
 
 NAMESPACE_BEGIN(nanogui)
diff --git a/src/widget.cpp b/src/widget.cpp
index 03af6b1..68318a8 100644
--- a/src/widget.cpp
+++ b/src/widget.cpp
@@ -16,6 +16,7 @@
 #include <nanogui/opengl.h>
 #include <nanogui/screen.h>
 #include <nanogui/serializer/core.h>
+#include <cassert>
 
 NAMESPACE_BEGIN(nanogui)