diff --git a/lib/OpenLayers/Map.js b/lib/OpenLayers/Map.js
index 086f674f30..fa2441d9d7 100644
--- a/lib/OpenLayers/Map.js
+++ b/lib/OpenLayers/Map.js
@@ -641,27 +641,47 @@ OpenLayers.Map.prototype = {
 
     /**
      * @returns A Bounds object which represents the lon/lat bounds of the 
-     *          current viewPort.
+     *          current viewPort. 
+     *          If no baselayer is set, returns null.
      * @type OpenLayers.Bounds
      */
     getExtent: function () {
-        return this.baseLayer.getExtent();
+        var extent = null;
+        
+        if (this.baseLayer != null) {
+            extent = this.baseLayer.getExtent();
+        }
+        return extent;
     },
 
     /**
-    * @type float
-    */
+     * @returns The current resolution of the map. 
+     *          If no baselayer is set, returns null.
+     * @type float
+     */
     getResolution: function () {
-        return this.baseLayer.getResolution();
+        var resolution = null;
+        
+        if (this.baseLayer != null) {
+            resolution = this.baseLayer.getResolution();
+        }
+        return resolution;
     },
 
     /**
     * @param {OpenLayers.Bounds} bounds
     *
+    * @returns A suitable zoom level for the specified bounds.
+    *          If no baselayer is set, returns null.
     * @type int
     */
     getZoomForExtent: function (bounds) {
-        return this.baseLayer.getZoomForExtent(bounds);        
+        zoom = null;
+        
+        if (this.baseLayer != null) {
+            zoom = this.baseLayer.getZoomForExtent(bounds);
+        }
+        return zoom;
     },
 
   /********************************************************/