diff --git a/lib/oauth.js b/lib/oauth.js
index 49c5b50..c705fe3 100644
--- a/lib/oauth.js
+++ b/lib/oauth.js
@@ -195,7 +195,7 @@ exports.OAuth.prototype._performSecureRequest= function( oauth_token, oauth_toke
     oauthProvider= this._createClient(parsedUrl.port, parsedUrl.hostname);
   }
 
-  var headers= {}
+  var headers= {};
 
   // build request authorization header
   var authHeader="OAuth "; 
@@ -212,7 +212,9 @@ exports.OAuth.prototype._performSecureRequest= function( oauth_token, oauth_toke
   headers["Host"] = parsedUrl.host
 
   for( var key in this._headers ) {
-    headers[key]= this._headers[key];
+    if (this._headers.hasOwnProperty(key)) {
+      headers[key]= this._headers[key];
+    }
   }
 
   headers["Content-length"]= post_body ? post_body.length : 0; //Probably going to fail if not posting ascii