diff --git a/default.nix b/default.nix
index 0bcde72..3eb74cd 100644
--- a/default.nix
+++ b/default.nix
@@ -26,6 +26,7 @@ let
 in
 {
   inherit pkgs;
+  tests = import ./tests { inherit pkgs; };
   shell = pkgs.mkShell {
     name = "binary-cache";
     buildInputs = check.enabledPackages;
diff --git a/tests/default.nix b/tests/default.nix
index 6e39f47..7a712b5 100644
--- a/tests/default.nix
+++ b/tests/default.nix
@@ -1,8 +1,8 @@
-let
-  sources = import ../npins;
-  inherit (sources) nixpkgs;
-  pkgs = import nixpkgs { overlays = [ (import ../pkgs/overlay.nix) ]; };
-in
+{
+  sources ? import ../npins,
+  nixpkgs ? sources.nixpkgs,
+  pkgs ? import nixpkgs { overlays = [ (import ../pkgs/overlay.nix) ]; },
+}:
 {
   basic = pkgs.callPackage ./basic.nix { };
   ingest = pkgs.callPackage ./ingest.nix { };