diff --git a/lib/OpenLayers/Map.js b/lib/OpenLayers/Map.js
index 22ee39810f..9895278124 100644
--- a/lib/OpenLayers/Map.js
+++ b/lib/OpenLayers/Map.js
@@ -458,7 +458,11 @@ OpenLayers.Map.prototype = {
     * @returns {OpenLayers.Size}
     */
     getSize: function () {
-        return this.size;
+        var size = null;
+        if (this.size != null) {
+            size = this.size.clone();
+        }
+        return size;
     },
 
     /**