diff --git a/PhoneNumber.js b/PhoneNumber.js
index 004564b..7afb66e 100644
--- a/PhoneNumber.js
+++ b/PhoneNumber.js
@@ -5,32 +5,32 @@ var PhoneNumber = (function (dataBase) {
   // Use strict in our context only - users might not want it
   'use strict';
 
-  const MAX_PHONE_NUMBER_LENGTH = 50;
-  const NON_ALPHA_CHARS = /[^a-zA-Z]/g;
-  const NON_DIALABLE_CHARS = /[^,#+\*\d]/g;
-  const NON_DIALABLE_CHARS_ONCE = new RegExp(NON_DIALABLE_CHARS.source);
-  const BACKSLASH = /\\/g;
-  const SPLIT_FIRST_GROUP = /^(\d+)(.*)$/;
-  const LEADING_PLUS_CHARS_PATTERN = /^[+\uFF0B]+/g;
+  var MAX_PHONE_NUMBER_LENGTH = 50;
+  var NON_ALPHA_CHARS = /[^a-zA-Z]/g;
+  var NON_DIALABLE_CHARS = /[^,#+\*\d]/g;
+  var NON_DIALABLE_CHARS_ONCE = new RegExp(NON_DIALABLE_CHARS.source);
+  var BACKSLASH = /\\/g;
+  var SPLIT_FIRST_GROUP = /^(\d+)(.*)$/;
+  var LEADING_PLUS_CHARS_PATTERN = /^[+\uFF0B]+/g;
 
   // Format of the string encoded meta data. If the name contains "^" or "$"
   // we will generate a regular expression from the value, with those special
   // characters as prefix/suffix.
-  const META_DATA_ENCODING = ["region",
-                              "^(?:internationalPrefix)",
-                              "nationalPrefix",
-                              "^(?:nationalPrefixForParsing)",
-                              "nationalPrefixTransformRule",
-                              "nationalPrefixFormattingRule",
-                              "^possiblePattern$",
-                              "^nationalPattern$",
-                              "formats"];
-
-  const FORMAT_ENCODING = ["^pattern$",
-                           "nationalFormat",
-                           "^leadingDigits",
-                           "nationalPrefixFormattingRule",
-                           "internationalFormat"];
+  var META_DATA_ENCODING = ["region",
+                            "^(?:internationalPrefix)",
+                            "nationalPrefix",
+                            "^(?:nationalPrefixForParsing)",
+                            "nationalPrefixTransformRule",
+                            "nationalPrefixFormattingRule",
+                            "^possiblePattern$",
+                            "^nationalPattern$",
+                            "formats"];
+
+  var FORMAT_ENCODING = ["^pattern$",
+                         "nationalFormat",
+                         "^leadingDigits",
+                         "nationalPrefixFormattingRule",
+                         "internationalFormat"];
 
   var regionCache = Object.create(null);
 
@@ -106,8 +106,8 @@ var PhoneNumber = (function (dataBase) {
               // the formats field from the main country.
               if (typeof entry[0] == "string")
                 entry[0] = ParseMetaData(countryCode, entry[0]);
-              let formats = entry[0].formats;
-              let current = ParseMetaData(countryCode, entry[n]);
+              var formats = entry[0].formats;
+              var current = ParseMetaData(countryCode, entry[n]);
               current.formats = formats;
               return entry[n] = current;
             }