diff --git a/src/game-lib-system-input.js b/src/game-lib-system-input.js
index 2389b0d..073ae38 100644
--- a/src/game-lib-system-input.js
+++ b/src/game-lib-system-input.js
@@ -641,10 +641,10 @@ GameLib.System.Input.prototype.onTouchMove = function (event) {
                     down += diffY;
                 }
 
-                this.touches[id].right += right;
-                this.touches[id].left += left;
-                this.touches[id].up += up;
-                this.touches[id].down += down;
+                this.touches[id].right = right;
+                this.touches[id].left = left;
+                this.touches[id].up = up;
+                this.touches[id].down = down;
                 this.touches[id].lastTouchX = event.changedTouches[id].pageX;
                 this.touches[id].lastTouchY = event.changedTouches[id].pageY;
                 this.touches[id].pageX = event.changedTouches[t].pageX;