diff --git a/src/ol/control/control.js b/src/ol/control/control.js
index 9fe4232b91..13465598c5 100644
--- a/src/ol/control/control.js
+++ b/src/ol/control/control.js
@@ -107,10 +107,10 @@ ol.control.Control.prototype.setMap = function(map) {
   if (this.map_) {
     goog.dom.removeNode(this.element);
   }
-  if (this.listenerKeys.length > 0) {
-    ol.events.unlistenByKey(this.listenerKeys);
-    this.listenerKeys.length = 0;
+  for (var i = 0, ii = this.listenerKeys.length; i < ii; ++i) {
+    ol.events.unlistenByKey(this.listenerKeys[i]);
   }
+  this.listenerKeys.length = 0;
   this.map_ = map;
   if (this.map_) {
     var target = this.target_ ?
diff --git a/src/ol/control/zoomslidercontrol.js b/src/ol/control/zoomslidercontrol.js
index 67329d0781..a68dc1a140 100644
--- a/src/ol/control/zoomslidercontrol.js
+++ b/src/ol/control/zoomslidercontrol.js
@@ -250,17 +250,15 @@ ol.control.ZoomSlider.prototype.handleDraggerStart_ = function(event) {
     this.dragging_ = true;
 
     if (!this.dragListenerKeys_) {
+      var drag = this.handleDraggerDrag_;
+      var end = this.handleDraggerEnd_;
       this.dragListenerKeys_ = [
-        ol.events.listen(document, [
-          ol.events.EventType.MOUSEMOVE,
-          ol.events.EventType.TOUCHMOVE,
-          ol.pointer.EventType.POINTERMOVE
-        ], this.handleDraggerDrag_, this),
-        ol.events.listen(document, [
-          ol.events.EventType.MOUSEUP,
-          ol.events.EventType.TOUCHEND,
-          ol.pointer.EventType.POINTERUP
-        ], this.handleDraggerEnd_, this)
+        ol.events.listen(document, ol.events.EventType.MOUSEMOVE, drag, this),
+        ol.events.listen(document, ol.events.EventType.TOUCHMOVE, drag, this),
+        ol.events.listen(document, ol.pointer.EventType.POINTERMOVE, drag, this),
+        ol.events.listen(document, ol.events.EventType.MOUSEUP, end, this),
+        ol.events.listen(document, ol.events.EventType.TOUCHEND, end, this),
+        ol.events.listen(document, ol.pointer.EventType.POINTERUP, end, this)
       ];
     }
   }
diff --git a/src/ol/deviceorientation.js b/src/ol/deviceorientation.js
index 6726ac59d8..faa1e92d1a 100644
--- a/src/ol/deviceorientation.js
+++ b/src/ol/deviceorientation.js
@@ -83,7 +83,7 @@ ol.DeviceOrientation = function(opt_options) {
 
   /**
    * @private
-   * @type {ol.events.Key}
+   * @type {?ol.events.Key}
    */
   this.listenerKey_ = null;
 
diff --git a/src/ol/events.js b/src/ol/events.js
index 8940bea04e..75fa70dcc9 100644
--- a/src/ol/events.js
+++ b/src/ol/events.js
@@ -2,7 +2,6 @@ goog.provide('ol.events');
 goog.provide('ol.events.EventType');
 goog.provide('ol.events.KeyCode');
 
-goog.require('goog.asserts');
 goog.require('goog.object');
 
 
@@ -74,7 +73,7 @@ ol.events.EventTargetLike;
 /**
  * Key to use with {@link ol.Observable#unByKey}.
  *
- * @typedef {ol.events.ListenerObjType|Array.<ol.events.ListenerObjType>}
+ * @typedef {ol.events.ListenerObjType}
  * @api
  */
 ol.events.Key;
@@ -157,6 +156,50 @@ ol.events.getListeners = function(target, type) {
 };
 
 
+/**
+ * Get the lookup of listeners.  If one does not exist on the target, it is
+ * created.
+ * @param {ol.events.EventTargetLike} target Target.
+ * @return {!Object.<string, Array.<ol.events.ListenerObjType>>} Map of
+ *     listeners by event type.
+ * @private
+ */
+ol.events.getListenerMap_ = function(target) {
+  var listenerMap = target[ol.events.LISTENER_MAP_PROP_];
+  if (!listenerMap) {
+    listenerMap = target[ol.events.LISTENER_MAP_PROP_] = {};
+  }
+  return listenerMap;
+};
+
+
+/**
+ * Clean up all listener objects of the given type.  All properties on the
+ * listener objects will be removed, and if no listeners remain in the listener
+ * map, it will be removed from the target.
+ * @param {ol.events.EventTargetLike} target Target.
+ * @param {ol.events.EventType|string} type Type.
+ * @private
+ */
+ol.events.removeListeners_ = function(target, type) {
+  var listeners = ol.events.getListeners(target, type);
+  if (listeners) {
+    for (var i = 0, ii = listeners.length; i < ii; ++i) {
+      target.removeEventListener(type, listeners[i].boundListener);
+      goog.object.clear(listeners[i])
+    }
+    listeners.length = 0;
+    var listenerMap = target[ol.events.LISTENER_MAP_PROP_];
+    if (listenerMap) {
+      delete listenerMap[type];
+      if (Object.keys(listenerMap).length === 0) {
+        delete target[ol.events.LISTENER_MAP_PROP_];
+      }
+    }
+  }
+};
+
+
 /**
  * Registers an event listener on an event target. Inspired by
  * {@link https://google.github.io/closure-library/api/source/closure/goog/events/events.js.src.html}
@@ -164,10 +207,8 @@ ol.events.getListeners = function(target, type) {
  * This function efficiently binds a `listener` to a `this` object, and returns
  * a key for use with {@link ol.events.unlistenByKey}.
  *
- * @param {EventTarget|ol.events.EventTarget|
- *     {removeEventListener: function(string, Function, boolean=)}} target
- *     Event target.
- * @param {ol.events.EventType|string|Array.<(ol.events.EventType|string)>} type
+ * @param {ol.events.EventTargetLike} target Event target.
+ * @param {ol.events.EventType|string} type
  *     Event type.
  * @param {ol.events.ListenerFunctionType} listener Listener.
  * @param {Object=} opt_this Object referenced by the `this` keyword in the
@@ -176,18 +217,7 @@ ol.events.getListeners = function(target, type) {
  * @return {ol.events.Key} Unique key for the listener.
  */
 ol.events.listen = function(target, type, listener, opt_this, opt_once) {
-  if (Array.isArray(type)) {
-    var keys = [];
-    type.forEach(function(t) {
-      keys.push(ol.events.listen(target, t, listener, opt_this, opt_once));
-    });
-    return keys;
-  }
-
-  var listenerMap = target[ol.events.LISTENER_MAP_PROP_];
-  if (!listenerMap) {
-    target[ol.events.LISTENER_MAP_PROP_] = listenerMap = {};
-  }
+  var listenerMap = ol.events.getListenerMap_(target);
   var listenerArray = listenerMap[type];
   if (!listenerArray) {
     listenerArray = listenerMap[type] = [];
@@ -229,8 +259,7 @@ ol.events.listen = function(target, type, listener, opt_this, opt_once) {
  * listener.
  *
  * @param {ol.events.EventTargetLike} target Event target.
- * @param {ol.events.EventType|string|Array.<(ol.events.EventType|string)>} type
- *     Event type.
+ * @param {ol.events.EventType|string} type Event type.
  * @param {ol.events.ListenerFunctionType} listener Listener.
  * @param {Object=} opt_this Object referenced by the `this` keyword in the
  *     listener. Default is the `target`.
@@ -250,20 +279,12 @@ ol.events.listenOnce = function(
  * arguments that were used for a previous {@link ol.events.listen} call.
  *
  * @param {ol.events.EventTargetLike} target Event target.
- * @param {ol.events.EventType|string|Array.<(ol.events.EventType|string)>} type
- *     Event type.
+ * @param {ol.events.EventType|string} type Event type.
  * @param {ol.events.ListenerFunctionType} listener Listener.
  * @param {Object=} opt_this Object referenced by the `this` keyword in the
  *     listener. Default is the `target`.
  */
 ol.events.unlisten = function(target, type, listener, opt_this) {
-  if (Array.isArray(type)) {
-    type.forEach(function(t) {
-      ol.events.unlisten(target, t, listener, opt_this);
-    });
-    return;
-  }
-  goog.asserts.assertString(type, 'type is a string');
   var listenerArray = ol.events.getListeners(target, type);
   if (listenerArray) {
     var listenerObj = ol.events.findListener_(listenerArray, listener,
@@ -282,25 +303,16 @@ ol.events.unlisten = function(target, type, listener, opt_this) {
  * The argument passed to this function is the key returned from
  * {@link ol.events.listen} or {@link ol.events.listenOnce}.
  *
- * @param {ol.events.Key} key Key or keys.
+ * @param {ol.events.Key} key The key.
  */
 ol.events.unlistenByKey = function(key) {
-  if (Array.isArray(key)) {
-    key.forEach(ol.events.unlistenByKey);
-    return;
-  }
-
   if (key && key.target) {
     key.target.removeEventListener(key.type, key.boundListener);
     var listenerArray = ol.events.getListeners(key.target, key.type);
     if (listenerArray) {
       ol.events.findListener_(listenerArray, key.listener, key.bindTo, true);
       if (listenerArray.length === 0) {
-        var listenerMap = key.target[ol.events.LISTENER_MAP_PROP_];
-        delete listenerMap[key.type];
-        if (Object.keys(listenerMap).length === 0) {
-          delete key.target[ol.events.LISTENER_MAP_PROP_];
-        }
+        ol.events.removeListeners_(key.target, key.type);
       }
     }
     goog.object.clear(key);
@@ -315,10 +327,8 @@ ol.events.unlistenByKey = function(key) {
  * @param {ol.events.EventTargetLike} target Target.
  */
 ol.events.unlistenAll = function(target) {
-  var listenerMap = target[ol.events.LISTENER_MAP_PROP_];
-  if (listenerMap) {
-    for (var type in listenerMap) {
-      ol.events.unlistenByKey(listenerMap[type]);
-    }
+  var listenerMap = ol.events.getListenerMap_(target);
+  for (var type in listenerMap) {
+    ol.events.removeListeners_(target, type);
   }
 };
diff --git a/src/ol/feature.js b/src/ol/feature.js
index 3cd97ebd2c..a99ff3747d 100644
--- a/src/ol/feature.js
+++ b/src/ol/feature.js
@@ -87,7 +87,7 @@ ol.Feature = function(opt_geometryOrProperties) {
 
   /**
    * @private
-   * @type {ol.events.Key}
+   * @type {?ol.events.Key}
    */
   this.geometryChangeKey_ = null;
 
diff --git a/src/ol/interaction/draganddropinteraction.js b/src/ol/interaction/draganddropinteraction.js
index 16819f9285..bab371d51e 100644
--- a/src/ol/interaction/draganddropinteraction.js
+++ b/src/ol/interaction/draganddropinteraction.js
@@ -153,8 +153,11 @@ ol.interaction.DragAndDrop.prototype.setMap = function(map) {
     this.dropListenKeys_ = [
       ol.events.listen(dropArea, ol.events.EventType.DROP,
           ol.interaction.DragAndDrop.handleDrop_, this),
-      ol.events.listen(dropArea, [ol.events.EventType.DRAGENTER,
-              ol.events.EventType.DRAGOVER, ol.events.EventType.DROP],
+      ol.events.listen(dropArea, ol.events.EventType.DRAGENTER,
+          ol.interaction.DragAndDrop.handleStop_, this),
+      ol.events.listen(dropArea, ol.events.EventType.DRAGOVER,
+          ol.interaction.DragAndDrop.handleStop_, this),
+      ol.events.listen(dropArea, ol.events.EventType.DROP,
           ol.interaction.DragAndDrop.handleStop_, this)
     ]
   }
diff --git a/src/ol/interaction/snapinteraction.js b/src/ol/interaction/snapinteraction.js
index 005195dde5..eb8598ade6 100644
--- a/src/ol/interaction/snapinteraction.js
+++ b/src/ol/interaction/snapinteraction.js
@@ -168,11 +168,13 @@ ol.interaction.Snap.prototype.addFeature = function(feature, opt_listen) {
     segmentWriter.call(this, feature, geometry);
 
     if (listen) {
-      this.geometryModifyListenerKeys_[feature_uid] = geometry.on(
+      this.geometryModifyListenerKeys_[feature_uid] = ol.events.listen(
+          geometry,
           ol.events.EventType.CHANGE,
           this.handleGeometryModify_.bind(this, feature),
           this);
-      this.geometryChangeListenerKeys_[feature_uid] = feature.on(
+      this.geometryChangeListenerKeys_[feature_uid] = ol.events.listen(
+          feature,
           ol.Object.getChangeEventType(feature.getGeometryName()),
           this.handleGeometryChange_, this);
     }
diff --git a/src/ol/layer/heatmaplayer.js b/src/ol/layer/heatmaplayer.js
index 7bdd5cafcd..a5daba97ea 100644
--- a/src/ol/layer/heatmaplayer.js
+++ b/src/ol/layer/heatmaplayer.js
@@ -83,10 +83,12 @@ ol.layer.Heatmap = function(opt_options) {
 
   this.setRadius(options.radius !== undefined ? options.radius : 8);
 
-  ol.events.listen(this, [
-    ol.Object.getChangeEventType(ol.layer.HeatmapLayerProperty.BLUR),
-    ol.Object.getChangeEventType(ol.layer.HeatmapLayerProperty.RADIUS)
-  ], this.handleStyleChanged_, this);
+  ol.events.listen(this,
+      ol.Object.getChangeEventType(ol.layer.HeatmapLayerProperty.BLUR),
+      this.handleStyleChanged_, this);
+  ol.events.listen(this,
+      ol.Object.getChangeEventType(ol.layer.HeatmapLayerProperty.RADIUS),
+      this.handleStyleChanged_, this);
 
   this.handleStyleChanged_();
 
diff --git a/src/ol/layer/layer.js b/src/ol/layer/layer.js
index 61e53335d9..61ae7a32c0 100644
--- a/src/ol/layer/layer.js
+++ b/src/ol/layer/layer.js
@@ -41,19 +41,19 @@ ol.layer.Layer = function(options) {
 
   /**
    * @private
-   * @type {ol.events.Key}
+   * @type {?ol.events.Key}
    */
   this.mapPrecomposeKey_ = null;
 
   /**
    * @private
-   * @type {ol.events.Key}
+   * @type {?ol.events.Key}
    */
   this.mapRenderKey_ = null;
 
   /**
    * @private
-   * @type {ol.events.Key}
+   * @type {?ol.events.Key}
    */
   this.sourceChangeKey_ = null;
 
@@ -164,13 +164,17 @@ ol.layer.Layer.prototype.handleSourcePropertyChange_ = function() {
  * @api
  */
 ol.layer.Layer.prototype.setMap = function(map) {
-  ol.events.unlistenByKey(this.mapPrecomposeKey_);
-  this.mapPrecomposeKey_ = null;
+  if (this.mapPrecomposeKey_) {
+    ol.events.unlistenByKey(this.mapPrecomposeKey_);
+    this.mapPrecomposeKey_ = null;
+  }
   if (!map) {
     this.changed();
   }
-  ol.events.unlistenByKey(this.mapRenderKey_);
-  this.mapRenderKey_ = null;
+  if (this.mapRenderKey_) {
+    ol.events.unlistenByKey(this.mapRenderKey_);
+    this.mapRenderKey_ = null;
+  }
   if (map) {
     this.mapPrecomposeKey_ = ol.events.listen(
         map, ol.render.EventType.PRECOMPOSE, function(evt) {
diff --git a/src/ol/map.js b/src/ol/map.js
index 6b8bbb470f..9397724a4f 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -243,7 +243,7 @@ ol.Map = function(options) {
 
   /**
    * @private
-   * @type {ol.events.Key}
+   * @type {?ol.events.Key}
    */
   this.viewPropertyListenerKey_ = null;
 
@@ -284,7 +284,7 @@ ol.Map = function(options) {
    */
   this.overlayContainerStopEvent_ = document.createElement('DIV');
   this.overlayContainerStopEvent_.className = 'ol-overlaycontainer-stopevent';
-  ol.events.listen(this.overlayContainerStopEvent_, [
+  var overlayEvents = [
     ol.events.EventType.CLICK,
     ol.events.EventType.DBLCLICK,
     ol.events.EventType.MOUSEDOWN,
@@ -292,13 +292,18 @@ ol.Map = function(options) {
     ol.events.EventType.MSPOINTERDOWN,
     ol.MapBrowserEvent.EventType.POINTERDOWN,
     goog.userAgent.GECKO ? 'DOMMouseScroll' : ol.events.EventType.MOUSEWHEEL
-  ], ol.events.Event.stopPropagation);
+  ];
+  for (var i = 0, ii = overlayEvents.length; i < ii; ++i) {
+    ol.events.listen(this.overlayContainerStopEvent_, overlayEvents[i],
+        ol.events.Event.stopPropagation);
+  }
   this.viewport_.appendChild(this.overlayContainerStopEvent_);
 
   var mapBrowserEventHandler = new ol.MapBrowserEventHandler(this);
-  ol.events.listen(mapBrowserEventHandler,
-      goog.object.getValues(ol.MapBrowserEvent.EventType),
-      this.handleMapBrowserEvent, this);
+  for (var key in ol.MapBrowserEvent.EventType) {
+    ol.events.listen(mapBrowserEventHandler, ol.MapBrowserEvent.EventType[key],
+        this.handleMapBrowserEvent, this);
+  }
   this.registerDisposable(mapBrowserEventHandler);
 
   /**
@@ -309,9 +314,9 @@ ol.Map = function(options) {
 
   /**
    * @private
-   * @type {ol.events.Key|undefined}
+   * @type {Array.<ol.events.Key>}
    */
-  this.keyHandlerKey_;
+  this.keyHandlerKeys_ = null;
 
   ol.events.listen(this.viewport_, ol.events.EventType.WHEEL,
       this.handleBrowserEvent, this);
@@ -1060,8 +1065,11 @@ ol.Map.prototype.handleTargetChanged_ = function() {
 
   var targetElement = this.getTargetElement();
 
-  if (this.keyHandlerKey_) {
-    ol.events.unlistenByKey(this.keyHandlerKey_);
+  if (this.keyHandlerKeys_) {
+    for (var i = 0, ii = this.keyHandlerKeys_.length; i < ii; ++i) {
+      ol.events.unlistenByKey(this.keyHandlerKeys_[i]);
+    }
+    this.keyHandlerKeys_ = null;
   }
 
   if (!targetElement) {
@@ -1076,9 +1084,12 @@ ol.Map.prototype.handleTargetChanged_ = function() {
 
     var keyboardEventTarget = !this.keyboardEventTarget_ ?
         targetElement : this.keyboardEventTarget_;
-    this.keyHandlerKey_ = ol.events.listen(keyboardEventTarget,
-        [ol.events.EventType.KEYDOWN, ol.events.EventType.KEYPRESS],
-        this.handleBrowserEvent, this);
+    this.keyHandlerKeys_ = [
+      ol.events.listen(keyboardEventTarget, ol.events.EventType.KEYDOWN,
+          this.handleBrowserEvent, this),
+      ol.events.listen(keyboardEventTarget, ol.events.EventType.KEYPRESS,
+          this.handleBrowserEvent, this)
+    ];
 
     if (!this.handleResize_) {
       this.handleResize_ = this.updateSize.bind(this);
diff --git a/src/ol/mapbrowserevent.js b/src/ol/mapbrowserevent.js
index 95bbadaed0..f6eef67ffd 100644
--- a/src/ol/mapbrowserevent.js
+++ b/src/ol/mapbrowserevent.js
@@ -154,7 +154,7 @@ ol.MapBrowserEventHandler = function(map) {
   this.dragListenerKeys_ = null;
 
   /**
-   * @type {ol.events.Key}
+   * @type {?ol.events.Key}
    * @private
    */
   this.pointerdownListenerKey_ = null;
diff --git a/src/ol/observable.js b/src/ol/observable.js
index 6281ce2452..0f3d53e273 100644
--- a/src/ol/observable.js
+++ b/src/ol/observable.js
@@ -35,11 +35,18 @@ goog.inherits(ol.Observable, ol.events.EventTarget);
 
 /**
  * Removes an event listener using the key returned by `on()` or `once()`.
- * @param {ol.events.Key} key The key returned by `on()` or `once()`.
+ * @param {ol.events.Key|Array.<ol.events.Key>} key The key returned by `on()`
+ *     or `once()` (or an array of keys).
  * @api stable
  */
 ol.Observable.unByKey = function(key) {
-  ol.events.unlistenByKey(key);
+  if (Array.isArray(key)) {
+    for (var i = 0, ii = key.length; i < ii; ++i) {
+      ol.events.unlistenByKey(key[i]);
+    }
+  } else {
+    ol.events.unlistenByKey(/** @type {ol.events.Key} */ (key));
+  }
 };
 
 
@@ -90,11 +97,23 @@ ol.Observable.prototype.getRevision = function() {
  * @param {string|Array.<string>} type The event type or array of event types.
  * @param {function(?): ?} listener The listener function.
  * @param {Object=} opt_this The object to use as `this` in `listener`.
- * @return {ol.events.Key} Unique key for the listener.
+ * @return {ol.events.Key|Array.<ol.events.Key>} Unique key for the listener. If
+ *     called with an array of event types as the first argument, the return
+ *     will be an array of keys.
  * @api stable
  */
 ol.Observable.prototype.on = function(type, listener, opt_this) {
-  return ol.events.listen(this, type, listener, opt_this);
+  if (Array.isArray(type)) {
+    var len = type.length;
+    var keys = new Array(len);
+    for (var i = 0; i < len; ++i) {
+      keys[i] = ol.events.listen(this, type[i], listener, opt_this);
+    }
+    return keys;
+  } else {
+    return ol.events.listen(
+        this, /** @type {string} */ (type), listener, opt_this);
+  }
 };
 
 
@@ -103,11 +122,23 @@ ol.Observable.prototype.on = function(type, listener, opt_this) {
  * @param {string|Array.<string>} type The event type or array of event types.
  * @param {function(?): ?} listener The listener function.
  * @param {Object=} opt_this The object to use as `this` in `listener`.
- * @return {ol.events.Key} Unique key for the listener.
+ * @return {ol.events.Key|Array.<ol.events.Key>} Unique key for the listener. If
+ *     called with an array of event types as the first argument, the return
+ *     will be an array of keys.
  * @api stable
  */
 ol.Observable.prototype.once = function(type, listener, opt_this) {
-  return ol.events.listenOnce(this, type, listener, opt_this);
+  if (Array.isArray(type)) {
+    var len = type.length;
+    var keys = new Array(len);
+    for (var i = 0; i < len; ++i) {
+      keys[i] = ol.events.listenOnce(this, type[i], listener, opt_this);
+    }
+    return keys;
+  } else {
+    return ol.events.listenOnce(
+        this, /** @type {string} */ (type), listener, opt_this);
+  }
 };
 
 
@@ -120,7 +151,14 @@ ol.Observable.prototype.once = function(type, listener, opt_this) {
  * @api stable
  */
 ol.Observable.prototype.un = function(type, listener, opt_this) {
-  ol.events.unlisten(this, type, listener, opt_this);
+  if (Array.isArray(type)) {
+    for (var i = 0, ii = type.length; i < ii; ++i) {
+      ol.events.unlisten(this, type[i], listener, opt_this);
+    }
+    return;
+  } else {
+    ol.events.unlisten(this, /** @type {string} */ (type), listener, opt_this);
+  }
 };
 
 
@@ -128,7 +166,8 @@ ol.Observable.prototype.un = function(type, listener, opt_this) {
  * Removes an event listener using the key returned by `on()` or `once()`.
  * Note that using the {@link ol.Observable.unByKey} static function is to
  * be preferred.
- * @param {ol.events.Key} key The key returned by `on()` or `once()`.
+ * @param {ol.events.Key|Array.<ol.events.Key>} key The key returned by `on()`
+ *     or `once()` (or an array of keys).
  * @function
  * @api stable
  */
diff --git a/src/ol/overlay.js b/src/ol/overlay.js
index 9bd2b78d21..1fdd1aa9d1 100644
--- a/src/ol/overlay.js
+++ b/src/ol/overlay.js
@@ -137,7 +137,7 @@ ol.Overlay = function(options) {
 
   /**
    * @private
-   * @type {ol.events.Key}
+   * @type {?ol.events.Key}
    */
   this.mapPostrenderListenerKey_ = null;
 
diff --git a/src/ol/reproj/image.js b/src/ol/reproj/image.js
index 7b8c32f52e..4d8b81581a 100644
--- a/src/ol/reproj/image.js
+++ b/src/ol/reproj/image.js
@@ -102,7 +102,7 @@ ol.reproj.Image = function(sourceProj, targetProj,
 
   /**
    * @private
-   * @type {ol.events.Key|null}
+   * @type {?ol.events.Key}
    */
   this.sourceListenerKey_ = null;
 
diff --git a/test/spec/ol/events.test.js b/test/spec/ol/events.test.js
index d4781811f8..2ee3f7a8fe 100644
--- a/test/spec/ol/events.test.js
+++ b/test/spec/ol/events.test.js
@@ -84,16 +84,9 @@ describe('ol.events', function() {
       ol.events.listen(target, 'foo', function() {});
       expect(add.callCount).to.be(1);
     });
-    it('adds listeners for multiple types with a single call', function() {
-      ol.events.listen(target, ['foo', 'bar'], function() {});
-      expect(add.getCall(0).args[0]).to.be('foo');
-      expect(add.getCall(1).args[0]).to.be('bar');
-    });
     it('returns a key', function() {
       var key = ol.events.listen(target, 'foo', function() {});
       expect(key).to.be.a(Object);
-      key = ol.events.listen(target, ['foo', 'bar'], function() {});
-      expect(key).to.be.a(Array);
     });
     it('does not add the same listener twice', function() {
       var listener = function() {};
@@ -173,12 +166,15 @@ describe('ol.events', function() {
 
   describe('unlistenAll()', function() {
     it('unregisters all listeners registered for a target', function() {
-      var key = ol.events.listen(target, ['foo', 'bar'], function() {});
+      var keys = [
+        ol.events.listen(target, 'foo', function() {}),
+        ol.events.listen(target, 'bar', function() {})
+      ];
       ol.events.unlistenAll(target);
       expect(ol.events.getListeners(target, 'foo')).to.be(undefined);
       expect(ol.events.getListeners(target, 'bar')).to.be(undefined);
       expect(ol.events.LISTENER_MAP_PROP_ in target).to.be(false);
-      expect(key).to.eql([{}, {}]);
+      expect(keys).to.eql([{}, {}]);
     });
   });