diff --git a/nixos/modules/services/web-apps/silverbullet.nix b/nixos/modules/services/web-apps/silverbullet.nix
index e1b795a30749..789fafb68f7f 100644
--- a/nixos/modules/services/web-apps/silverbullet.nix
+++ b/nixos/modules/services/web-apps/silverbullet.nix
@@ -24,7 +24,7 @@ in
       };
 
       listenPort = lib.mkOption {
-        type = lib.types.int;
+        type = lib.types.port;
         default = 3000;
         description = "Port to listen on.";
       };