--- a/gui-x11/x11.c
+++ b/gui-x11/x11.c
@@ -1004,8 +1004,12 @@ xmouse(XEvent *e)
 		ms.buttons |= 1;
 	if(s & Button2Mask)
 		ms.buttons |= 2;
-	if(s & Button3Mask)
-		ms.buttons |= 4;
+	if(s & Button3Mask){
+		if (s & ShiftMask)
+			ms.buttons |= 2;
+		else
+			ms.buttons |= 4;
+	}
 	if(s & Button4Mask)
 		ms.buttons |= 8;
 	if(s & Button5Mask)
