diff --git a/machines/cray/configuration.nix b/machines/cray/configuration.nix
index 3832a2b..44eaf8c 100644
--- a/machines/cray/configuration.nix
+++ b/machines/cray/configuration.nix
@@ -2,7 +2,9 @@
 # your system.  Help is available in the configuration.nix(5) man page
 # and in the NixOS manual (accessible by running ‘nixos-help’).
 
-{ config, pkgs, ... }:
+{ sources ? import ../../nix
+, pkgs ? sources.pkgs {}
+, ... } :
 
 {
   imports = [
@@ -20,6 +22,11 @@
   boot.loader.systemd-boot.enable = true;
   boot.loader.efi.canTouchEfiVariables = true;
 
+  # for nvidia drivers
+  #nixpkgs.config.allowUnfree = true;
+
+  #services.xserver.videoDrivers = [ "nvidia" ];
+
   # Set your time zone.
   time.timeZone = "Europe/Berlin";
 
diff --git a/nix/sources.json b/nix/sources.json
index 67241b4..a71aaf7 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -23,4 +23,4 @@
         "url": "https://github.com/nmattia/niv/archive/5830a4dd348d77e39a0f3c4c762ff2663b602d4c.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     }
-}
\ No newline at end of file
+}