diff --git a/users/multi/whitby/home-manager.nix b/users/multi/whitby/home-manager.nix
index 765c0e839..13e313281 100644
--- a/users/multi/whitby/home-manager.nix
+++ b/users/multi/whitby/home-manager.nix
@@ -1,4 +1,4 @@
-{ config, pkgs, depot, ... }:
+{ config ? throw "not a readTree target", pkgs, depot, ... }:
 
 let
   hmPath = "$HOME/nix/home-manager";