diff --git a/src/osgPlugins/Inventor/ConvertToInventor.cpp b/src/osgPlugins/Inventor/ConvertToInventor.cpp
index c5e5b34aa..3e1c80410 100644
--- a/src/osgPlugins/Inventor/ConvertToInventor.cpp
+++ b/src/osgPlugins/Inventor/ConvertToInventor.cpp
@@ -79,6 +79,8 @@
 #endif
 #include "ConvertToInventor.h"
 
+#include <assert.h>
+
 
 #define DEBUG_IV_WRITER 1