diff --git a/public/js/ff/charts.defaults.js b/public/js/ff/charts.defaults.js
index e2764d5567..3070d20e5c 100644
--- a/public/js/ff/charts.defaults.js
+++ b/public/js/ff/charts.defaults.js
@@ -31,6 +31,7 @@
  */
 function formatLabel(str, maxwidth) {
     var sections = [];
+    str = String(str);
     var words = str.split(" ");
     var temp = "";