diff --git a/systems/pi400/default.nix b/systems/pi400/default.nix
index 1dd934f..3761024 100644
--- a/systems/pi400/default.nix
+++ b/systems/pi400/default.nix
@@ -71,6 +71,7 @@
 
   services.nix-serve = {
     enable = true;
+    openFirewall = true;
     secretKeyFile = "/var/cache-priv-key.pem";
   };