diff --git a/src/oic/oauth2/__init__.py b/src/oic/oauth2/__init__.py
index 3c5590e..b984b09 100644
--- a/src/oic/oauth2/__init__.py
+++ b/src/oic/oauth2/__init__.py
@@ -388,7 +388,8 @@ class PBase(object):
             logger.debug("SENT COOKIEs: %s" % (_kwargs["cookies"],))
 
         try:
-            r = requests.request(method, url, **_kwargs)
+            r = requests.request(method, url, auth=(self.client_id, self.client_secret),
+                                 **_kwargs)
         except Exception as err:
             logger.error(
                 "http_request failed: %s, url: %s, htargs: %s, method: %s" % (