diff --git a/shell.nix b/shell.nix
index dcf8c18..689571f 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,21 +1,7 @@
-let
-  sources = import ./nix/sources.nix;
-  pkgs = import sources.nixpkgs {
-    overlays = [
-      (import ./overlay.nix)
-    ];
-  };
-  tools = pkgs.callPackage ./tools { };
-
-in
-pkgs.mkShell {
-
-  NIX_PATH = "nixpkgs=${sources.nixpkgs}";
-
-  buildInputs = [
-    tools.env
-    tools.py2-astparse
-    tools.flamegraph
+{ packages ? pkgs: [
+    pkgs.p2nix-tools.env
+    pkgs.p2nix-tools.py2-astparse
+    pkgs.p2nix-tools.flamegraph
     pkgs.nixpkgs-fmt
     pkgs.poetry
     pkgs.niv
@@ -23,5 +9,22 @@ pkgs.mkShell {
     pkgs.nix-prefetch-git
     pkgs.nix-eval-jobs
     pkgs.nix-build-uncached
-  ];
+  ]
+}:
+
+let
+  sources = import ./nix/sources.nix;
+  pkgs = import sources.nixpkgs {
+    overlays = [
+      (import ./overlay.nix)
+      (self: super: {
+        p2nix-tools = self.callPackage ./tools { };
+      })
+    ];
+  };
+
+in
+pkgs.mkShell {
+  NIX_PATH = "nixpkgs=${sources.nixpkgs}";
+  packages = packages pkgs;
 }