diff --git a/lib/helpers.js b/lib/helpers.js
index bcc24c6..dbb84ec 100644
--- a/lib/helpers.js
+++ b/lib/helpers.js
@@ -5,7 +5,7 @@ var qs    = require("querystring")
 module.exports = function(config){
   var root    = config.root || "sandbox"
   var signer  = oauth(config.app_key, config.app_secret)
-  var scope   = config.scope
+  var scope   = config.scope = config.scope || ""
   
   return {  
     sign: function(token, args){