diff --git a/include/osgGLUT/glut b/include/osgGLUT/glut
index caddfc641..003ea6d1a 100644
--- a/include/osgGLUT/glut
+++ b/include/osgGLUT/glut
@@ -5,6 +5,8 @@
 #ifndef OSG_GLUT
 #define OSG_GLUT 1
 
+#include <stdlib.h>
+
 #if defined(__DARWIN_OSX__)
     #include <GLUT/glut.h>
 #else