diff --git a/src/ol/control/scalelinecontrol.js b/src/ol/control/scalelinecontrol.js
index 4f43d8ce3d..37f779a2f0 100644
--- a/src/ol/control/scalelinecontrol.js
+++ b/src/ol/control/scalelinecontrol.js
@@ -77,7 +77,7 @@ ol.control.ScaleLine = function(opt_options) {
    * @private
    * @type {number|undefined}
    */
-  this.renderedWidth_;
+  this.renderedWidth_ = undefined;
 
   /**
    * @private
diff --git a/src/ol/control/zoomslidercontrol.js b/src/ol/control/zoomslidercontrol.js
index 5fb6a454ea..5af6be81e6 100644
--- a/src/ol/control/zoomslidercontrol.js
+++ b/src/ol/control/zoomslidercontrol.js
@@ -38,10 +38,10 @@ ol.control.ZoomSlider = function(options) {
   /**
    * Will hold the current resolution of the view.
    *
-   * @type {number}
+   * @type {number|undefined}
    * @private
    */
-  this.currentResolution_;
+  this.currentResolution_ = undefined;
 
   /**
    * The direction of the slider. Will be determined from actual display of the
diff --git a/src/ol/geolocation.js b/src/ol/geolocation.js
index a619db1b1f..81bdc95d1b 100644
--- a/src/ol/geolocation.js
+++ b/src/ol/geolocation.js
@@ -49,7 +49,7 @@ ol.Geolocation = function() {
    * @private
    * @type {number|undefined}
    */
-  this.watchId_;
+  this.watchId_ = undefined;
 
   this.setTracking(false);
 
diff --git a/src/ol/interaction/dragrotateandzoominteraction.js b/src/ol/interaction/dragrotateandzoominteraction.js
index f7f64c0cc4..4e67f01c27 100644
--- a/src/ol/interaction/dragrotateandzoominteraction.js
+++ b/src/ol/interaction/dragrotateandzoominteraction.js
@@ -29,13 +29,13 @@ ol.interaction.DragRotateAndZoom = function(condition) {
    * @private
    * @type {number|undefined}
    */
-  this.lastAngle_;
+  this.lastAngle_ = undefined;
 
   /**
    * @private
    * @type {number|undefined}
    */
-  this.lastMagnitude_;
+  this.lastMagnitude_ = undefined;
 
 };
 goog.inherits(ol.interaction.DragRotateAndZoom, ol.interaction.Drag);
diff --git a/src/ol/interaction/touchrotateinteraction.js b/src/ol/interaction/touchrotateinteraction.js
index 166ff7111e..d7ffb146f5 100644
--- a/src/ol/interaction/touchrotateinteraction.js
+++ b/src/ol/interaction/touchrotateinteraction.js
@@ -38,7 +38,7 @@ ol.interaction.TouchRotate = function(opt_threshold) {
    * @private
    * @type {number|undefined}
    */
-  this.lastAngle_;
+  this.lastAngle_ = undefined;
 
   /**
    * @private
diff --git a/src/ol/interaction/touchzoominteraction.js b/src/ol/interaction/touchzoominteraction.js
index 8585bef32b..d68e2f853d 100644
--- a/src/ol/interaction/touchzoominteraction.js
+++ b/src/ol/interaction/touchzoominteraction.js
@@ -36,7 +36,7 @@ ol.interaction.TouchZoom = function() {
    * @private
    * @type {number|undefined}
    */
-  this.lastDistance_;
+  this.lastDistance_ = undefined;
 
   /**
    * @private