diff --git a/flake.nix b/flake.nix
index ef5839c..5f10bbd 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,13 +1,13 @@
 {
   inputs = {
-    nixpkgs.url = "flake:nixpkgs/nixos-23.11";
+    nixpkgs.url = "flake:nixpkgs/nixos-23.05";
     nixpkgs-unstable.url = "flake:nixpkgs/nixos-unstable";
     utils.url = "github:gytis-ivaskevicius/flake-utils-plus/v1.4.0";
     simple-nixos-mailserver = {
-      url = "gitlab:simple-nixos-mailserver/nixos-mailserver/nixos-23.11";
+      url = "gitlab:simple-nixos-mailserver/nixos-mailserver/nixos-23.05";
       inputs = {
         nixpkgs.follows = "nixpkgs-unstable";
-        nixpkgs-23_11.follows = "nixpkgs";
+        nixpkgs-23_05.follows = "nixpkgs";
       };
     };
     dogetipbot-telegram = {
diff --git a/systems/LoutreOS/configuration.nix b/systems/LoutreOS/configuration.nix
index ed50563..134a76d 100644
--- a/systems/LoutreOS/configuration.nix
+++ b/systems/LoutreOS/configuration.nix
@@ -29,6 +29,9 @@
 
   documentation.nixos.enable = false;
 
+  nixpkgs.config.allowUnfree = false;
+  nixpkgs.config.allowUnfreePredicate = (pkg: builtins.elem pkg.pname or (builtins.parseDrvName pkg.name).name [ "factorio-headless" "perl5.32.1-slimserver" "minecraft-server" ]);
+
   services.zfs = {
     autoSnapshot.enable = true;
     autoScrub = {