diff --git a/nixos/modules/services/mail/mailman.nix b/nixos/modules/services/mail/mailman.nix
index ec2a19f58bb1..a61c45a43bb2 100644
--- a/nixos/modules/services/mail/mailman.nix
+++ b/nixos/modules/services/mail/mailman.nix
@@ -314,7 +314,7 @@ in {
         queue_dir = "$var_dir/queue";
         template_dir = "$var_dir/templates";
         log_dir = "/var/log/mailman";
-        lock_dir = "$var_dir/lock";
+        lock_dir = "/run/mailman/lock";
         etc_dir = "/etc";
         pid_file = "/run/mailman/master.pid";
       };
diff --git a/nixos/tests/mailman.nix b/nixos/tests/mailman.nix
index 2806e9166d9a..f9b43861a12f 100644
--- a/nixos/tests/mailman.nix
+++ b/nixos/tests/mailman.nix
@@ -63,5 +63,11 @@ import ./make-test-python.nix {
         wait_for_api()
         machine.succeed("curl --fail-with-body -sLSu restadmin:secretpassword http://localhost:8001/3.1/domains")
         machine.succeed("curl --fail-with-body -sILS http://localhost/")
+
+    with subtest("service locking"):
+        machine.fail("su -s /bin/sh -c 'mailman start' mailman")
+        machine.execute("systemctl kill --signal=SIGKILL mailman")
+        machine.succeed("systemctl restart mailman")
+        wait_for_api()
   '';
 }