1 files changed, 7 insertions, 13 deletions
diff --git a/lass/1systems/blue/source.nix b/lass/1systems/blue/source.nix
index a52771a4d..21f3a8bd5 100644
--- a/lass/1systems/blue/source.nix
+++ b/lass/1systems/blue/source.nix
@@ -1,20 +1,14 @@
 { lib, pkgs, ... }:
 {
   nixpkgs = lib.mkForce {
-    derivation = let
-      rev = (lib.importJSON ../../../krebs/nixpkgs.json).rev;
-      sha256 = (lib.importJSON ../../../krebs/nixpkgs.json).sha256;
-    in ''
-      with import (builtins.fetchTarball {
-        url = "https://github.com/nixos/nixpkgs/archive/${rev}.tar.gz";
-        sha256 = "${sha256}";
-      }) {};
-      pkgs.fetchFromGitHub {
+    file = {
+      path = toString (pkgs.fetchFromGitHub {
         owner = "nixos";
         repo = "nixpkgs";
-        rev = "${rev}";
-        sha256 = "${sha256}";
-      }
-    '';
+        rev = (lib.importJSON ../../../krebs/nixpkgs.json).rev;
+        sha256 = (lib.importJSON ../../../krebs/nixpkgs.json).sha256;
+      });
+      useChecksum = true;
+    };
   };
 }