diff --git a/nixos/modules/services/web-apps/discourse.nix b/nixos/modules/services/web-apps/discourse.nix
index 49958fc6190..9c7166f381a 100644
--- a/nixos/modules/services/web-apps/discourse.nix
+++ b/nixos/modules/services/web-apps/discourse.nix
@@ -356,7 +356,7 @@ in
           };
 
           port = lib.mkOption {
-            type = lib.types.int;
+            type = lib.types.port;
             default = 25;
             description = ''
               The port of the SMTP server Discourse should use to