diff --git a/src/osg/GraphicsContext.cpp b/src/osg/GraphicsContext.cpp
index 277673c79..8777fe096 100644
--- a/src/osg/GraphicsContext.cpp
+++ b/src/osg/GraphicsContext.cpp
@@ -11,6 +11,7 @@
  * OpenSceneGraph Public License for more details.
 */
 
+#include <stdlib.h>
 
 #include <osg/GraphicsContext>
 #include <osg/Camera>