diff --git a/modules/nixos/mcpo/default.nix b/modules/nixos/mcpo/default.nix
index 86e943f..76ad953 100644
--- a/modules/nixos/mcpo/default.nix
+++ b/modules/nixos/mcpo/default.nix
@@ -106,7 +106,7 @@ in
       after = [ "network.target" ];
       wantedBy = [ "multi-user.target" ];
       serviceConfig = {
-        ExecStart = "${getExe cfg.package} --port ${cfg.port} --config ${configFile}";
+        ExecStart = "${getExe cfg.package} --port ${toString cfg.port} --config ${configFile}";
         Restart = "on-failure";
         User = cfg.user;
         Group = cfg.group;