diff --git a/core/gesture.js b/core/gesture.js
index 127bbf36b..d983e7a2d 100644
--- a/core/gesture.js
+++ b/core/gesture.js
@@ -69,7 +69,7 @@ Blockly.Gesture = function(e, creatorWorkspace) {
    * @type {goog.math.Coordinate}
    * @private
    */
-  this.currentDragDeltaXY_ = 0;
+  this.currentDragDeltaXY_ = null;
 
   /**
    * The bubble that the gesture started on, or null if it did not start on a