diff --git a/mail-server.nix b/mail-server.nix
index 0501d7f..8a36737 100644
--- a/mail-server.nix
+++ b/mail-server.nix
@@ -1,7 +1,9 @@
 { config, lib, pkgs, ... }@toplevel:
 
 with lib;
-let cfg = config.fudo.mail;
+let
+  cfg = config.fudo.mail;
+  hostname = config.instance.hostname;
 
 in {
   options.fudo.mail = with types; {