diff --git a/src/views/graphs.js b/src/views/graphs.js
index d82f572e8..040d6adaf 100644
--- a/src/views/graphs.js
+++ b/src/views/graphs.js
@@ -157,7 +157,7 @@ angular.module('Application').controller('GraphsController', ['$scope', '$locati
                     });
 
                     // get disk usage data
-                    const graphiteQueries = disk.contains.map(function (content) {
+                    var graphiteQueries = disk.contains.map(function (content) {
                         return 'absolute(collectd.localhost.du-' + content.id + '.capacity-usage)';
                     });