well, my channels.nix have it declared like this: ```nix home-manager = let try = builtins.tryEval ; hm = if try.success then try.value else nixpkgs.fetchFromGitHub { owner = "rycee"; repo = "home-manager"; rev = "cba7b6ee6e056421f862b008b45f1ff9cc2e7252"; sha256 = "1q7diljdkj0q7d7k79rghx3yp683p6q8dg43h8h1bklzrywxir8a"; }; in hm; ```