diff --git a/src/ol/control/control.js b/src/ol/control/control.js
index 6efdad3caf..abd9ee5171 100644
--- a/src/ol/control/control.js
+++ b/src/ol/control/control.js
@@ -2,6 +2,7 @@ goog.provide('ol.control.Control');
 
 goog.require('goog.dom');
 goog.require('goog.events');
+goog.require('ol');
 goog.require('ol.MapEventType');
 goog.require('ol.Object');
 
@@ -67,7 +68,7 @@ ol.control.Control = function(options) {
   /**
    * @type {function(ol.MapEvent)}
    */
-  this.render = options.render ? options.render : goog.nullFunction;
+  this.render = options.render ? options.render : ol.nullFunction;
 
   if (options.target) {
     this.setTarget(options.target);
@@ -116,7 +117,7 @@ ol.control.Control.prototype.setMap = function(map) {
     var target = !goog.isNull(this.target_) ?
         this.target_ : map.getOverlayContainerStopEvent();
     goog.dom.appendChild(target, this.element);
-    if (this.render !== goog.nullFunction) {
+    if (this.render !== ol.nullFunction) {
       this.listenerKeys.push(goog.events.listen(map,
           ol.MapEventType.POSTRENDER, this.render, false, this));
     }
diff --git a/src/ol/interaction/dragboxinteraction.js b/src/ol/interaction/dragboxinteraction.js
index afc0b4e6b3..7aa5eb19be 100644
--- a/src/ol/interaction/dragboxinteraction.js
+++ b/src/ol/interaction/dragboxinteraction.js
@@ -152,7 +152,7 @@ ol.interaction.DragBox.prototype.getGeometry = function() {
  * @param {ol.MapBrowserEvent} mapBrowserEvent Map browser event.
  * @protected
  */
-ol.interaction.DragBox.prototype.onBoxEnd = goog.nullFunction;
+ol.interaction.DragBox.prototype.onBoxEnd = ol.nullFunction;
 
 
 /**
diff --git a/src/ol/interaction/pointerinteraction.js b/src/ol/interaction/pointerinteraction.js
index 18cff5509d..f9af8002dc 100644
--- a/src/ol/interaction/pointerinteraction.js
+++ b/src/ol/interaction/pointerinteraction.js
@@ -2,6 +2,7 @@ goog.provide('ol.interaction.Pointer');
 
 goog.require('goog.functions');
 goog.require('goog.object');
+goog.require('ol');
 goog.require('ol.MapBrowserEvent.EventType');
 goog.require('ol.MapBrowserPointerEvent');
 goog.require('ol.Pixel');
@@ -144,7 +145,7 @@ ol.interaction.Pointer.prototype.updateTrackedPointers_ =
  * @param {ol.MapBrowserPointerEvent} mapBrowserEvent Event.
  * @this {ol.interaction.Pointer}
  */
-ol.interaction.Pointer.handleDragEvent = goog.nullFunction;
+ol.interaction.Pointer.handleDragEvent = ol.nullFunction;
 
 
 /**
@@ -167,7 +168,7 @@ ol.interaction.Pointer.handleDownEvent = goog.functions.FALSE;
  * @param {ol.MapBrowserPointerEvent} mapBrowserEvent Event.
  * @this {ol.interaction.Pointer}
  */
-ol.interaction.Pointer.handleMoveEvent = goog.nullFunction;
+ol.interaction.Pointer.handleMoveEvent = ol.nullFunction;
 
 
 /**
diff --git a/src/ol/ol.js b/src/ol/ol.js
index e3b9f8be1f..cffdecbc29 100644
--- a/src/ol/ol.js
+++ b/src/ol/ol.js
@@ -221,3 +221,11 @@ ol.WEBGL_EXTENSIONS; // value is set in `ol.has`
 ol.inherits =
     goog.inherits;
 // note that the newline above is necessary to satisfy the linter
+
+
+/**
+ * A reusable function, used e.g. as a default for callbacks.
+ *
+ * @return {undefined} Nothing.
+ */
+ol.nullFunction = function() {};
diff --git a/src/ol/render/canvas/canvasreplay.js b/src/ol/render/canvas/canvasreplay.js
index fede3fe1aa..7948cc3edb 100644
--- a/src/ol/render/canvas/canvasreplay.js
+++ b/src/ol/render/canvas/canvasreplay.js
@@ -12,6 +12,7 @@ goog.require('goog.array');
 goog.require('goog.asserts');
 goog.require('goog.object');
 goog.require('goog.vec.Mat4');
+goog.require('ol');
 goog.require('ol.array');
 goog.require('ol.color');
 goog.require('ol.dom');
@@ -585,7 +586,7 @@ ol.render.canvas.Replay.prototype.endGeometry = function(geometry, feature) {
 /**
  * FIXME empty description for jsdoc
  */
-ol.render.canvas.Replay.prototype.finish = goog.nullFunction;
+ol.render.canvas.Replay.prototype.finish = ol.nullFunction;
 
 
 /**
diff --git a/src/ol/renderer/dom/domlayerrenderer.js b/src/ol/renderer/dom/domlayerrenderer.js
index 991ceef4e9..f269acd53c 100644
--- a/src/ol/renderer/dom/domlayerrenderer.js
+++ b/src/ol/renderer/dom/domlayerrenderer.js
@@ -1,5 +1,6 @@
 goog.provide('ol.renderer.dom.Layer');
 
+goog.require('ol');
 goog.require('ol.layer.Layer');
 goog.require('ol.renderer.Layer');
 
@@ -28,14 +29,14 @@ goog.inherits(ol.renderer.dom.Layer, ol.renderer.Layer);
 /**
  * Clear rendered elements.
  */
-ol.renderer.dom.Layer.prototype.clearFrame = goog.nullFunction;
+ol.renderer.dom.Layer.prototype.clearFrame = ol.nullFunction;
 
 
 /**
  * @param {olx.FrameState} frameState Frame state.
  * @param {ol.layer.LayerState} layerState Layer state.
  */
-ol.renderer.dom.Layer.prototype.composeFrame = goog.nullFunction;
+ol.renderer.dom.Layer.prototype.composeFrame = ol.nullFunction;
 
 
 /**
diff --git a/src/ol/renderer/layerrenderer.js b/src/ol/renderer/layerrenderer.js
index 81fd1fb375..7014f88789 100644
--- a/src/ol/renderer/layerrenderer.js
+++ b/src/ol/renderer/layerrenderer.js
@@ -4,6 +4,7 @@ goog.require('goog.asserts');
 goog.require('goog.events');
 goog.require('goog.events.EventType');
 goog.require('goog.functions');
+goog.require('ol');
 goog.require('ol.ImageState');
 goog.require('ol.Observable');
 goog.require('ol.TileRange');
@@ -47,7 +48,7 @@ goog.inherits(ol.renderer.Layer, ol.Observable);
  * @return {T|undefined} Callback result.
  * @template S,T
  */
-ol.renderer.Layer.prototype.forEachFeatureAtCoordinate = goog.nullFunction;
+ol.renderer.Layer.prototype.forEachFeatureAtCoordinate = ol.nullFunction;
 
 
 /**
diff --git a/src/ol/renderer/maprenderer.js b/src/ol/renderer/maprenderer.js
index 4fb7150b6e..bd2a57adb5 100644
--- a/src/ol/renderer/maprenderer.js
+++ b/src/ol/renderer/maprenderer.js
@@ -335,7 +335,7 @@ ol.renderer.Map.prototype.removeLayerRendererByKey_ = function(layerKey) {
  * Render.
  * @param {?olx.FrameState} frameState Frame state.
  */
-ol.renderer.Map.prototype.renderFrame = goog.nullFunction;
+ol.renderer.Map.prototype.renderFrame = ol.nullFunction;
 
 
 /**
diff --git a/src/ol/source/source.js b/src/ol/source/source.js
index 98dc3124ec..38261a0e12 100644
--- a/src/ol/source/source.js
+++ b/src/ol/source/source.js
@@ -1,6 +1,7 @@
 goog.provide('ol.source.Source');
 goog.provide('ol.source.State');
 
+goog.require('ol');
 goog.require('ol.Attribution');
 goog.require('ol.Object');
 goog.require('ol.proj');
@@ -92,8 +93,7 @@ goog.inherits(ol.source.Source, ol.Object);
  * @return {T|undefined} Callback result.
  * @template T
  */
-ol.source.Source.prototype.forEachFeatureAtCoordinate =
-    goog.nullFunction;
+ol.source.Source.prototype.forEachFeatureAtCoordinate = ol.nullFunction;
 
 
 /**
diff --git a/src/ol/source/tilesource.js b/src/ol/source/tilesource.js
index ad707f5042..b9cb312290 100644
--- a/src/ol/source/tilesource.js
+++ b/src/ol/source/tilesource.js
@@ -4,6 +4,7 @@ goog.provide('ol.source.TileOptions');
 
 goog.require('goog.asserts');
 goog.require('goog.events.Event');
+goog.require('ol');
 goog.require('ol.Attribution');
 goog.require('ol.Extent');
 goog.require('ol.TileCache');
@@ -244,7 +245,7 @@ ol.source.Tile.prototype.getTileCoordForTileUrlFunction =
  * @param {number} x Tile coordinate x.
  * @param {number} y Tile coordinate y.
  */
-ol.source.Tile.prototype.useTile = goog.nullFunction;
+ol.source.Tile.prototype.useTile = ol.nullFunction;
 
 
 
diff --git a/src/ol/source/vectorsource.js b/src/ol/source/vectorsource.js
index 53b3ca3f62..5bfe84441d 100644
--- a/src/ol/source/vectorsource.js
+++ b/src/ol/source/vectorsource.js
@@ -11,6 +11,7 @@ goog.require('goog.events');
 goog.require('goog.events.Event');
 goog.require('goog.events.EventType');
 goog.require('goog.object');
+goog.require('ol');
 goog.require('ol.Collection');
 goog.require('ol.CollectionEventType');
 goog.require('ol.Extent');
@@ -89,7 +90,7 @@ ol.source.Vector = function(opt_options) {
    * @private
    * @type {ol.FeatureLoader}
    */
-  this.loader_ = goog.nullFunction;
+  this.loader_ = ol.nullFunction;
 
   if (options.loader !== undefined) {
     this.loader_ = options.loader;
diff --git a/src/ol/style/circlestyle.js b/src/ol/style/circlestyle.js
index 34eb334b87..08de4b1aa1 100644
--- a/src/ol/style/circlestyle.js
+++ b/src/ol/style/circlestyle.js
@@ -3,6 +3,7 @@ goog.provide('ol.style.Circle');
 goog.require('goog.asserts');
 goog.require('goog.dom');
 goog.require('goog.dom.TagName');
+goog.require('ol');
 goog.require('ol.color');
 goog.require('ol.has');
 goog.require('ol.render.canvas');
@@ -214,19 +215,19 @@ ol.style.Circle.prototype.getStroke = function() {
 /**
  * @inheritDoc
  */
-ol.style.Circle.prototype.listenImageChange = goog.nullFunction;
+ol.style.Circle.prototype.listenImageChange = ol.nullFunction;
 
 
 /**
  * @inheritDoc
  */
-ol.style.Circle.prototype.load = goog.nullFunction;
+ol.style.Circle.prototype.load = ol.nullFunction;
 
 
 /**
  * @inheritDoc
  */
-ol.style.Circle.prototype.unlistenImageChange = goog.nullFunction;
+ol.style.Circle.prototype.unlistenImageChange = ol.nullFunction;
 
 
 /**
diff --git a/src/ol/style/regularshapestyle.js b/src/ol/style/regularshapestyle.js
index 2994738547..c3da2c16a6 100644
--- a/src/ol/style/regularshapestyle.js
+++ b/src/ol/style/regularshapestyle.js
@@ -3,6 +3,7 @@ goog.provide('ol.style.RegularShape');
 goog.require('goog.asserts');
 goog.require('goog.dom');
 goog.require('goog.dom.TagName');
+goog.require('ol');
 goog.require('ol.color');
 goog.require('ol.has');
 goog.require('ol.render.canvas');
@@ -270,19 +271,19 @@ ol.style.RegularShape.prototype.getStroke = function() {
 /**
  * @inheritDoc
  */
-ol.style.RegularShape.prototype.listenImageChange = goog.nullFunction;
+ol.style.RegularShape.prototype.listenImageChange = ol.nullFunction;
 
 
 /**
  * @inheritDoc
  */
-ol.style.RegularShape.prototype.load = goog.nullFunction;
+ol.style.RegularShape.prototype.load = ol.nullFunction;
 
 
 /**
  * @inheritDoc
  */
-ol.style.RegularShape.prototype.unlistenImageChange = goog.nullFunction;
+ol.style.RegularShape.prototype.unlistenImageChange = ol.nullFunction;
 
 
 /**