diff --git a/install/conf/ipa.conf b/install/conf/ipa.conf
index e1f1a581b..75c122e6c 100644
--- a/install/conf/ipa.conf
+++ b/install/conf/ipa.conf
@@ -117,6 +117,7 @@ Alias /ipa/session/cookie "/usr/share/ipa/gssapi.login"
   NSSVerifyClient require
   NSSUserName SSL_CLIENT_CERT
   LookupUserByCertificate On
+  LookupUserByCertificateParamName "username"
   WSGIProcessGroup ipa
   WSGIApplicationGroup ipa
   GssapiImpersonate On