diff --git a/lib/cartodb/controllers/layergroup.js b/lib/cartodb/controllers/layergroup.js
index 79268d6e..fb1aab9b 100644
--- a/lib/cartodb/controllers/layergroup.js
+++ b/lib/cartodb/controllers/layergroup.js
@@ -56,7 +56,7 @@ LayergroupController.prototype.register = function(app) {
         this.tile.bind(this));
 
     app.get(app.base_url_mapconfig +
-        '/:token/:z/:x/:y.:format', cors(), userMiddleware,
+        '/:token/:z/:x/:y.(:format)', cors(), userMiddleware,
         this.tile.bind(this));
 
     app.get(app.base_url_mapconfig +