diff --git a/oauth2/__init__.py b/oauth2/__init__.py
index 835270e3..d7e31a56 100644
--- a/oauth2/__init__.py
+++ b/oauth2/__init__.py
@@ -637,7 +637,8 @@ def set_signature_method(self, method):
         self.method = method
 
     def request(self, uri, method="GET", body='', headers=None, 
-        redirections=httplib2.DEFAULT_MAX_REDIRECTS, connection_type=None):
+        redirections=httplib2.DEFAULT_MAX_REDIRECTS, connection_type=None,
+        realm=None):
         DEFAULT_POST_CONTENT_TYPE = 'application/x-www-form-urlencoded'
 
         if not isinstance(headers, dict):
@@ -668,7 +669,7 @@ def request(self, uri, method="GET", body='', headers=None,
             hierpart = ''
         host, rest = urllib.splithost(rest)
 
-        realm = schema + ':' + hierpart + host
+        realm = realm if realm != None else schema + ':' + hierpart + host
 
         if is_form_encoded:
             body = req.to_postdata()