diff --git a/lib/cartodb/controllers/named_maps.js b/lib/cartodb/controllers/named_maps.js
index 0c5e739f..cda71346 100644
--- a/lib/cartodb/controllers/named_maps.js
+++ b/lib/cartodb/controllers/named_maps.js
@@ -41,8 +41,10 @@ function NamedMapsController(prepareContext, namedMapProviderCache, tileBackend,
 module.exports = NamedMapsController;
 
 NamedMapsController.prototype.register = function(app) {
+    const { base_url_mapconfig, base_url_templated } = app;
+
     app.get(
-        app.base_url_templated + '/:template_id/:layer/:z/:x/:y.(:format)',
+        `${base_url_templated}/:template_id/:layer/:z/:x/:y.(:format)`,
         cors(),
         userMiddleware(),
         this.prepareContext,
@@ -65,7 +67,7 @@ NamedMapsController.prototype.register = function(app) {
     );
 
     app.get(
-        app.base_url_mapconfig + '/static/named/:template_id/:width/:height.:format',
+        `${base_url_mapconfig}/static/named/:template_id/:width/:height.:format`,
         cors(),
         userMiddleware(),
         allowQueryParams(['layer', 'zoom', 'lon', 'lat', 'bbox']),