diff --git a/lib/cartodb/models/mapconfig/adapter/mapconfig-buffer-size-adapter.js b/lib/cartodb/models/mapconfig/adapter/mapconfig-buffer-size-adapter.js
index 02ce6443..5b961ac4 100644
--- a/lib/cartodb/models/mapconfig/adapter/mapconfig-buffer-size-adapter.js
+++ b/lib/cartodb/models/mapconfig/adapter/mapconfig-buffer-size-adapter.js
@@ -1,16 +1,15 @@
 function MapConfigBufferSizeAdapter() {
+    this.formats = ['png', 'png32', 'mvt', 'grid.json'];
 }
 
 module.exports = MapConfigBufferSizeAdapter;
 
-var formats = ['png', 'png32', 'mvt', 'grid.json'];
-
 MapConfigBufferSizeAdapter.prototype.getMapConfig = function (user, requestMapConfig, params, context, callback) {
     if (!context.templateParams || !context.templateParams.buffersize) {
         return callback(null, requestMapConfig);
     }
 
-    formats.forEach(function (format) {
+    this.formats.forEach(function (format) {
         if (Number.isFinite(context.templateParams.buffersize[format])) {
             requestMapConfig.buffersize[format] = context.templateParams.buffersize[format];
         }