diff --git a/lib/OpenLayers/Layer/ArcGISCache.js b/lib/OpenLayers/Layer/ArcGISCache.js
index 46ca08a237..86f9567edb 100644
--- a/lib/OpenLayers/Layer/ArcGISCache.js
+++ b/lib/OpenLayers/Layer/ArcGISCache.js
@@ -271,7 +271,7 @@ OpenLayers.Layer.ArcGISCache = OpenLayers.Class(OpenLayers.Layer.XYZ, {
             endTileCol: end.x,
             endTileRow: end.y
         };
-        return calculateMaxExtentWithLOD(lod);
+        return this.calculateMaxExtentWithLOD(lod);
    },
     
     /**