diff --git a/src/core/math/Matrix.js b/src/core/math/Matrix.js
index f634729..ba28c1c 100644
--- a/src/core/math/Matrix.js
+++ b/src/core/math/Matrix.js
@@ -129,8 +129,11 @@
 {
     newPos = newPos || new Point();
 
-    newPos.x = this.a * pos.x + this.c * pos.y + this.tx;
-    newPos.y = this.b * pos.x + this.d * pos.y + this.ty;
+    var x = pos.x;
+    var y = pos.y;
+
+    newPos.x = this.a * x + this.c * y + this.tx;
+    newPos.y = this.b * x + this.d * y + this.ty;
 
     return newPos;
 };