diff --git a/nova/auth/users.py b/nova/auth/users.py
index 1fc97345..1a270733 100644
--- a/nova/auth/users.py
+++ b/nova/auth/users.py
@@ -100,6 +100,10 @@ flags.DEFINE_string('credential_cert_file', 'cert.pem',
                     'Filename of certificate in credentials zip')
 flags.DEFINE_string('credential_rc_file', 'novarc',
                     'Filename of rc in credentials zip')
+flags.DEFINE_string('credential_cert_subject',
+                    '/C=US/ST=California/L=MountainView/O=AnsoLabs/'
+                    'OU=NovaDev/CN=%s-%s'
+                    'Subject for certificate for users')
 flags.DEFINE_string('vpn_ip', '127.0.0.1',
                     'Public IP for the cloudpipe VPN servers')
 
@@ -516,7 +520,7 @@ class UserManager(object):
 
     def __cert_subject(self, uid):
         # FIXME(ja) - this should be pulled from a global configuration
-        return "/C=US/ST=California/L=MountainView/O=AnsoLabs/OU=NovaDev/CN=%s-%s" % (uid, str(datetime.datetime.utcnow().isoformat()))
+        return FLAGS.credential_cert_subject % (uid, utils.isotime())
 
 
 class LDAPWrapper(object):