diff --git a/Gui/wm/ws.h b/Gui/wm/ws.h
index f836848b28..17ad5a512a 100644
--- a/Gui/wm/ws.h
+++ b/Gui/wm/ws.h
@@ -29,11 +29,11 @@
 #define  wsPRMouseButton 3
 #define  wsP4MouseButton 4
 #define  wsP5MouseButton 5
-#define  wsRLMouseButton 1 + 128
-#define  wsRMMouseButton 2 + 128
-#define  wsRRMouseButton 3 + 128
-#define  wsR4MouseButton 4 + 128
-#define  wsR5MouseButton 5 + 128
+#define  wsRLMouseButton (1 + 128)
+#define  wsRMMouseButton (2 + 128)
+#define  wsRRMouseButton (3 + 128)
+#define  wsR4MouseButton (4 + 128)
+#define  wsR5MouseButton (5 + 128)
 #define  wsEnterWindow   253
 #define  wsLeaveWindow   254
 #define  wsMoveMouse     255