--- a/urllib2_kerberos.py

+++ b/urllib2_kerberos.py

@@ -34,6 +34,7 @@ class AbstractKerberosAuthHandler:

         """checks for "Negotiate" in proper auth header

         """

         authreqs = headers.getheaders(self.auth_header)

+        log.debug('authreqs = {}'.format(authreqs))

         if authreqs:

@@ -126,7 +127,8 @@ class AbstractKerberosAuthHandler:

             req.add_unredirected_header(self.authz_header, neg_hdr)

             resp = self.parent.open(req)

-            self.authenticate_server(resp.info())

+            if resp.getcode() != 200:

+                self.authenticate_server(resp.info())

             return resp