diff --git a/src/osgSim/ShapeAttribute.cpp b/src/osgSim/ShapeAttribute.cpp
index 8aa796902..b55f3651d 100644
--- a/src/osgSim/ShapeAttribute.cpp
+++ b/src/osgSim/ShapeAttribute.cpp
@@ -12,6 +12,7 @@
 */
 
 #include <memory.h>
+#include <stdlib.h>
 
 #include <osgSim/ShapeAttribute>