diff --git a/default.nix b/default.nix
index 3e51f46..f4d5739 100644
--- a/default.nix
+++ b/default.nix
@@ -1,4 +1,6 @@
-{ pkgs ? import <nixpkgs> {} }:
+{ pkgs ? import <nixpkgs> {},
+  extraDeps ? []
+}:
 
 let
   pypkgs = pkgs.python38Packages;
@@ -6,5 +8,5 @@ in pypkgs.buildPythonPackage {
   name = "intake";
   src = builtins.path { path = ./.; name = "intake"; };
   format = "pyproject";
-  propagatedBuildInputs = with pypkgs; [ setuptools ];
+  propagatedBuildInputs = with pypkgs; [ flask setuptools ] ++ extraDeps;
 }
diff --git a/shell.nix b/shell.nix
index 3a1f595..757aabc 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,8 +1,12 @@
 { pkgs ? import <nixpkgs> {} }:
 
 let
-  intake = import ./default.nix {};
-in pkgs.mkShell {
-  inputsFrom = [ intake ];
-  buildInputs = [ pkgs.nixos-shell ];
-}
+  extraDeps = [
+    pkgs.nixos-shell
+    pkgs.python38Packages.black
+    pkgs.python38Packages.pytest
+  ];
+  intake = import ./default.nix {
+    inherit pkgs extraDeps;
+  };
+in intake