diff --git a/direct/src/plugin/p3dCInstance.h b/direct/src/plugin/p3dCInstance.h
index 976b14007e..ed6f0a856e 100755
--- a/direct/src/plugin/p3dCInstance.h
+++ b/direct/src/plugin/p3dCInstance.h
@@ -21,6 +21,7 @@
 #include "pvector.h"
 
 #include <Python.h>
+#define TIXML_USE_STL
 #include <tinyxml.h>
 
 class P3DSession;