diff --git a/mozilla/modules/plugin/samples/default/os2/dialogs.cpp b/mozilla/modules/plugin/samples/default/os2/dialogs.cpp
index 29bc84223eb..b02f4ad1e91 100644
--- a/mozilla/modules/plugin/samples/default/os2/dialogs.cpp
+++ b/mozilla/modules/plugin/samples/default/os2/dialogs.cpp
@@ -38,6 +38,7 @@
 #define INCL_WIN
 #include <os2.h>
 #include <string.h>
+#include <assert.h>
 
 #include "npnulos2.h"
 
diff --git a/mozilla/modules/plugin/samples/default/os2/npshell.cpp b/mozilla/modules/plugin/samples/default/os2/npshell.cpp
index 99859bc98be..1318b9d593b 100644
--- a/mozilla/modules/plugin/samples/default/os2/npshell.cpp
+++ b/mozilla/modules/plugin/samples/default/os2/npshell.cpp
@@ -37,6 +37,7 @@
 
 #include <os2.h>
 #include <string.h>
+#include <assert.h>
 
 #include "npnulos2.h"