diff --git a/lib/querystring.js b/lib/querystring.js
index 4246e96..0b15e76 100644
--- a/lib/querystring.js
+++ b/lib/querystring.js
@@ -10,6 +10,11 @@
 
 exports.version = '0.3.1';
 
+/**
+ * Decode function.
+ */
+exports.decoder = decodeURIComponent;
+
 /**
  * Object#toString() ref for stringify().
  */
@@ -45,7 +50,7 @@ exports.parse = function(str){
     .split('&')
     .reduce(function(ret, pair){
       try{ 
-        pair = decodeURIComponent(pair.replace(/\+/g, ' '));
+        pair = exports.decoder(pair.replace(/\+/g, ' '));
       } catch(e) {
         // ignore
       }