diff --git a/lib/cartodb/backends/filter-stats.js b/lib/cartodb/backends/filter-stats.js
index 9c410362..76179ff3 100644
--- a/lib/cartodb/backends/filter-stats.js
+++ b/lib/cartodb/backends/filter-stats.js
@@ -24,9 +24,8 @@ function getEstimatedRows(pgQueryRunner, username, query, callback) {
 
 FilterStatsBackends.prototype.getFilterStats = function (username, unfiltered_query, filters, callback) {
     var stats = {};
-    var self = this;
 
-    getEstimatedRows(self.pgQueryRunner, username, unfiltered_query, function (err, rows) {
+    getEstimatedRows(this.pgQueryRunner, username, unfiltered_query, (err, rows) => {
         if (err){
             return callback(err);
         }
@@ -37,7 +36,7 @@ FilterStatsBackends.prototype.getFilterStats = function (username, unfiltered_qu
             var analysisFilter = new AnalysisFilter(filters);
             var query = analysisFilter.sql(unfiltered_query);
 
-            getEstimatedRows(self.pgQueryRunner, username, query, function (err, rows) {
+            getEstimatedRows(this.pgQueryRunner, username, query, (err, rows) => {
                 if (err){
                     return callback(err);
                 }