diff --git a/src/ol/map.js b/src/ol/map.js
index c6026a7e7f..335cb64873 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -261,7 +261,7 @@ ol.Map = function(options) {
   this.viewportSizeMonitor_ = new goog.dom.ViewportSizeMonitor();
 
   goog.events.listen(this.viewportSizeMonitor_, goog.events.EventType.RESIZE,
-      this.handleBrowserWindowResize, false, this);
+      this.updateSize, false, this);
 
   /**
    * @private
@@ -305,7 +305,7 @@ ol.Map = function(options) {
   this.setValues(optionsInternal.values);
 
   // this gives the map an initial size
-  this.handleBrowserWindowResize();
+  this.updateSize();
 
   if (goog.isDef(optionsInternal.controls)) {
     goog.array.forEach(optionsInternal.controls,
@@ -619,15 +619,6 @@ ol.Map.prototype.handleBackgroundColorChanged_ = function() {
 };
 
 
-/**
- * @protected
- */
-ol.Map.prototype.handleBrowserWindowResize = function() {
-  var size = goog.style.getSize(this.target_);
-  this.setSize(new ol.Size(size.width, size.height));
-};
-
-
 /**
  * @private
  */
@@ -871,6 +862,16 @@ ol.Map.prototype.unfreezeRendering = function() {
 };
 
 
+/**
+ * Force a recalculation of the map viewport size.  This should be called when
+ * third-party code changes the size of the map viewport.
+ */
+ol.Map.prototype.updateSize = function() {
+  var size = goog.style.getSize(this.target_);
+  this.setSize(new ol.Size(size.width, size.height));
+};
+
+
 /**
  * @param {function(this: T)} f Function.
  * @param {T=} opt_obj Object.