diff --git a/lib/oauth2.js b/lib/oauth2.js
index 94ed662c..4810bc27 100644
--- a/lib/oauth2.js
+++ b/lib/oauth2.js
@@ -163,7 +163,8 @@ exports.OAuth2.prototype.getAuthorizeUrl= function( params ) {
 exports.OAuth2.prototype.getOAuthAccessToken= function(code, params, callback) {
   var params= params || {};
   params['client_id'] = this._clientId;
-  params['client_secret'] = this._clientSecret;
+  if ( this._clientSecret )
+    params['client_secret'] = this._clientSecret;
   var codeParam = (params.grant_type === 'refresh_token') ? 'refresh_token' : 'code';
   params[codeParam]= code;