--- ./src/msw/textctrl.cpp	2013-01-02 21:47:03.000000000 +0100
+++ ./src/msw/textctrl.cpp	2013-01-02 21:46:53.000000000 +0100
@@ -992,7 +992,7 @@
 
     EDITSTREAM eds;
     wxZeroMemory(eds);
-    eds.dwCookie = (DWORD)&data;
+    eds.dwCookie = (DWORD_PTR)&data;
     eds.pfnCallback = wxRichEditStreamOut;
 
     ::SendMessage