--- a/src/linux/rw_x11.c
+++ b/src/linux/rw_x11.c
@@ -989,8 +989,8 @@
 	} 
 	else 
 	  {
-	    mx -= ((int)event.xmotion.x + mwx)*2;
-	    my -= ((int)event.xmotion.y + mwy)*2;
+	    mx += ((int)event.xmotion.x - mwx)*2;
+	    my += ((int)event.xmotion.y - mwy)*2;
 	    mwx = event.xmotion.x;
 	    mwy = event.xmotion.y;