diff --git a/lib/OpenLayers/Control/CacheWrite.js b/lib/OpenLayers/Control/CacheWrite.js
index 5a7a57c565..8b4e787e2f 100644
--- a/lib/OpenLayers/Control/CacheWrite.js
+++ b/lib/OpenLayers/Control/CacheWrite.js
@@ -173,11 +173,13 @@ OpenLayers.Control.CacheWrite = OpenLayers.Class(OpenLayers.Control, {
                 try {
                     var canvasContext = tile.getCanvasContext();
                     if (canvasContext) {
+                        var urlMap = OpenLayers.Control.CacheWrite.urlMap;
+                        var url = urlMap[tile.url] || tile.url;
                         window.localStorage.setItem(
-                            "olCache_" + OpenLayers.Control.CacheWrite.urlMap[tile.url],
+                            "olCache_" + url,
                             canvasContext.canvas.toDataURL(this.imageFormat)
                         );
-                        delete OpenLayers.Control.CacheWrite.urlMap[tile.url];
+                        delete urlMap[tile.url];
                     }
                 } catch(e) {
                     // local storage full or CORS violation