diff --git a/lib/oauth2.js b/lib/oauth2.js
index 77241c43..43c1f88e 100644
--- a/lib/oauth2.js
+++ b/lib/oauth2.js
@@ -183,7 +183,8 @@ exports.OAuth2.prototype.getOAuthAccessToken= function(code, params, callback) {
 
   var post_data= querystring.stringify( params );
   var post_headers= {
-       'Content-Type': 'application/x-www-form-urlencoded'
+       'Content-Type': 'application/x-www-form-urlencoded',
+       'Authorization': 'Basic ' + Buffer.from(params['client_id'] + ':' + params['client_secret']).toString('base64')
    };