diff --git a/lib/OpenLayers/Layer.js b/lib/OpenLayers/Layer.js
index 79388df452..9816053725 100644
--- a/lib/OpenLayers/Layer.js
+++ b/lib/OpenLayers/Layer.js
@@ -278,7 +278,7 @@ OpenLayers.Layer.prototype = {
      */
     getResolution: function() {
         var viewSize = this.map.getSize();
-        var extent = this.map.getExtent();
+        var extent = this.getExtent();
         return Math.max( extent.getWidth()  / viewSize.w,
                          extent.getHeight() / viewSize.h );
     },