diff --git a/contrib/testing/smtp-dane-mta-sts-check.py b/contrib/testing/smtp-dane-mta-sts-check.py
index 773baef..8cc5344 100755
--- a/contrib/testing/smtp-dane-mta-sts-check.py
+++ b/contrib/testing/smtp-dane-mta-sts-check.py
@@ -391,6 +391,7 @@ def write_dns_configs(directory: Path, trust_anchor: str) -> None:
         f'  pidfile: "{directory / "unbound.pid"}"\n'
         f'  logfile: "{directory / "unbound.log"}"\n'
         "  use-syslog: no\n"
+        '  local-zone: "test." nodefault\n'
         f'  trust-anchor-file: "{directory / "anchor"}"\n'
         "stub-zone:\n"
         f'  name: "{ZONE}."\n'