diff --git a/shell.nix b/shell.nix
index f047fa0..bcf1a40 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,4 +1,4 @@
-{ pkgs ? import <nixpkgs> {} }:
+{ pkgs ? import (fetchTarball https://nixos.org/channels/nixos-unstable/nixexprs.tar.xz) {} }:
   pkgs.mkShell {
     # nativeBuildInputs is usually what you want -- tools you need to run
     nativeBuildInputs = with pkgs.buildPackages; [