diff --git a/lib/program.js b/lib/program.js
index efda864..f44ade4 100644
--- a/lib/program.js
+++ b/lib/program.js
@@ -151,8 +151,8 @@ Program.prototype._bindMouse = function(s) {
     key.x = x - 32;
     key.y = y - 32;
 
-    if (key.x === 0) key.x = 255;
-    if (key.y === 0) key.y = 255;
+    if (key.x === -32) key.x = 255;
+    if (key.y === -32) key.y = 255;
 
     mod = b >> 3;
     key.shift = mod & 4;