diff --git a/lib/cartodb/controllers/named_maps.js b/lib/cartodb/controllers/named_maps.js
index 03008261..af281a02 100644
--- a/lib/cartodb/controllers/named_maps.js
+++ b/lib/cartodb/controllers/named_maps.js
@@ -333,7 +333,9 @@ NamedMapsController.prototype.getImage = function (label) {
     }.bind(this);
 };
 
-const incrementMapViewsError = ctx => `ERROR: failed to increment mapview count for user '${ctx.user}': ${ctx.err}`;
+function incrementMapViewsError (ctx) {
+    return `ERROR: failed to increment mapview count for user '${ctx.user}': ${ctx.err}`;
+}
 
 NamedMapsController.prototype.incrementMapViews = function () {
     return function incrementMapViewsMiddleware(req, res, next) {