diff --git a/src/ol/interaction/modifyinteraction.js b/src/ol/interaction/modifyinteraction.js
index e42e778512..6c8be757f4 100644
--- a/src/ol/interaction/modifyinteraction.js
+++ b/src/ol/interaction/modifyinteraction.js
@@ -194,7 +194,7 @@ ol.interaction.Modify = function(options) {
    * @type {Array}
    * @private
    */
-  this.dragSegments_ = null;
+  this.dragSegments_ = [];
 
   /**
    * Draw overlay where sketch features are drawn.