diff --git a/k5test/realm.py b/k5test/realm.py
index d8f7eee..41155f2 100644
--- a/k5test/realm.py
+++ b/k5test/realm.py
@@ -499,6 +499,7 @@ def _kdc_conf(self):
                     "kdc_ports": "$port0",
                     "kdc_tcp_ports": "$port0",
                     "database_name": "$tmpdir/db",
+                    "max_renewable_life": "7d",
                 }
             },
             "dbmodules": {