diff -up CEGUI-0.6.2/include/CEGUIBase.h~ CEGUI-0.6.2/include/CEGUIBase.h
--- CEGUI-0.6.2/include/CEGUIBase.h~	2008-02-11 15:38:27.000000000 +0100
+++ CEGUI-0.6.2/include/CEGUIBase.h	2011-02-13 20:06:29.477851548 +0100
@@ -33,6 +33,7 @@
 #ifndef _CEGUIBase_h_
 #define _CEGUIBase_h_
 
+#include <cstddef>
 #include <cassert>
 
 // bring in configuration options