diff --git a/include/wx/defs.h b/include/wx/defs.h
index 57918e7389..ca96e9e6e5 100644
--- a/include/wx/defs.h
+++ b/include/wx/defs.h
@@ -1057,6 +1057,10 @@ enum wxStretch
  */
 #define wxBU_AUTODRAW        0x0004
 #define wxBU_NOAUTODRAW      0x0000
+#define wxBU_LEFT            0x0040
+#define wxBU_TOP             0x0080
+#define wxBU_RIGHT           0x0100
+#define wxBU_BOTTOM          0x0200
 
 /*
  * wxTreeCtrl flags