diff --git a/src/ol/interaction/dragrotateinteraction.js b/src/ol/interaction/dragrotateinteraction.js
index 476cf1778f..d5815a08c8 100644
--- a/src/ol/interaction/dragrotateinteraction.js
+++ b/src/ol/interaction/dragrotateinteraction.js
@@ -23,7 +23,7 @@ goog.require('ol.interaction.Pointer');
  */
 ol.interaction.DragRotate = function(opt_options) {
 
-  var options = goog.isDef(opt_options) ? opt_options : {};
+  var options = opt_options ? opt_options : {};
 
   goog.base(this, {
     handleDownEvent: ol.interaction.DragRotate.handleDownEvent_,
@@ -35,7 +35,7 @@ ol.interaction.DragRotate = function(opt_options) {
    * @private
    * @type {ol.events.ConditionType}
    */
-  this.condition_ = goog.isDef(options.condition) ?
+  this.condition_ = options.condition ?
       options.condition : ol.events.condition.altShiftKeysOnly;
 
   /**
@@ -48,7 +48,7 @@ ol.interaction.DragRotate = function(opt_options) {
    * @private
    * @type {number}
    */
-  this.duration_ = goog.isDef(options.duration) ? options.duration : 250;
+  this.duration_ = options.duration ? options.duration : 250;
 };
 goog.inherits(ol.interaction.DragRotate, ol.interaction.Pointer);
 
@@ -68,7 +68,7 @@ ol.interaction.DragRotate.handleDragEvent_ = function(mapBrowserEvent) {
   var offset = mapBrowserEvent.pixel;
   var theta =
       Math.atan2(size[1] / 2 - offset[1], offset[0] - size[0] / 2);
-  if (goog.isDef(this.lastAngle_)) {
+  if (this.lastAngle_ !== undefined) {
     var delta = theta - this.lastAngle_;
     var view = map.getView();
     var rotation = view.getRotation();