diff --git a/addons/godot_xterm/native/shell.nix b/addons/godot_xterm/native/shell.nix
index 91b3d1c..baba829 100644
--- a/addons/godot_xterm/native/shell.nix
+++ b/addons/godot_xterm/native/shell.nix
@@ -1,5 +1,6 @@
-with (import <nixpkgs> {});
-mkShell {
+let
+  pkgs = import (fetchTarball("https://github.com/NixOS/nixpkgs/archive/09cd65b33c5653d7d2954fef4b9f0e718c899743.tar.gz")) {};
+in pkgs.mkShell {
   buildInputs = with pkgs; [
     git
     scons