diff --git a/custom/default.nix b/custom/default.nix
index 4f22b25..cb5f006 100644
--- a/custom/default.nix
+++ b/custom/default.nix
@@ -1,4 +1,4 @@
-{ pkgs ? import <nixos-unstable> { inherit system; }
+{ pkgs ? import <nixos> { inherit system; }
 , system ? builtins.currentSystem
 }:
 
diff --git a/custom/update-background/default.nix b/custom/update-background/default.nix
index 1ef856a..1a74946 100644
--- a/custom/update-background/default.nix
+++ b/custom/update-background/default.nix
@@ -14,7 +14,11 @@ let
 in
 writeScript "update-background.sh" ''
   #!/bin/sh
-  image=`${find} ${backgrounds_directory} -type f | ${grep} -v "/\." | ${shuf} -n 1`
+  if [ $# -eq 0 ]; then
+    image=`${find} ${backgrounds_directory} -type f | ${grep} -v "/\." | ${shuf} -n 1`
+  else
+    image="$1"
+  fi
   echo "image: $image"
   ${feh}/bin/feh --bg-fill --no-fehbg "$image"
   ${glib}/bin/gsettings set org.gnome.desktop.background picture-uri "file://$image"