diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..152ef91
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,10 @@
+{ pkgs ? import <nixpkgs> {} }:
+pkgs.mkShell {
+  name = "python-shell";
+  buildInputs = with pkgs; [
+    python38
+    python38Packages.tox
+    python38Packages.setuptools
+    python38Packages.virtualenv
+  ];
+}
diff --git a/tox.ini b/tox.ini
index 750d30f..9eb8750 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,6 +2,7 @@
 envlist = py38
 
 [testenv]
+passenv = PYTHONPATH
 deps =
 	pytest
 	flake8