diff --git a/lib/utils.js b/lib/utils.js
index 83fbd167..284de066 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -175,5 +175,5 @@ exports.cache = {
  * @private
  */
 exports.hyphenToCamel = function (str) {
-  return str.replace(/-[a-z]/g, (match) => { return match[1].toUpperCase(); });
+  return str.replace(/-[a-z]/g, function (match) { return match[1].toUpperCase(); });
 };