diff --git a/lib/OpenLayers/Events.js b/lib/OpenLayers/Events.js
index bd8a6d6d6d..0f1baca085 100644
--- a/lib/OpenLayers/Events.js
+++ b/lib/OpenLayers/Events.js
@@ -929,6 +929,7 @@ OpenLayers.Events = OpenLayers.Class({
      * calculated values.
      */
     getTouchClientXY: function (evt) {
+        // olMochWin is to override window, used for testing
         var win = window.olMockWin || window,
             winPageX = win.pageXOffset,
             winPageY = win.pageYOffset,