diff --git a/source/Ox/js/Encoding.js b/source/Ox/js/Encoding.js
index 697f45e3..974108ac 100644
--- a/source/Ox/js/Encoding.js
+++ b/source/Ox/js/Encoding.js
@@ -244,7 +244,7 @@ Ox.decodeDeflate = function(string, callback) {
 (function() {
 
     function replace(string) {
-        return string.replace(/%(?![0-9A-Fa-f]{2})/g, '%25')
+        return string.toString().replace(/%(?![0-9A-Fa-f]{2})/g, '%25')
             .replace(/(%[0-9A-Fa-f]{2})+/g, function(match) {
                 var hex = match.split('%').slice(1), ret;
                 Ox.forEach(Ox.range(1, hex.length + 1), function(length) {