diff --git a/lass/1systems/blue/source.nix b/lass/1systems/blue/source.nix
index 1a98fc058..2b4158211 100644
--- a/lass/1systems/blue/source.nix
+++ b/lass/1systems/blue/source.nix
@@ -11,4 +11,7 @@
       useChecksum = true;
     };
   });
+  nixpkgs-unstable = lib.mkForce {
+    file.path = "/var/empty";
+  };
 }