use NUR as an overlay

configuration.nix

@@ -1,4 +1,4 @@
-{ pkgs, config, ... }: {
+{ pkgs, outputs, config, ... }: {
   imports =
     [
       ./hardware-configuration.nix
@@ -116,4 +116,27 @@
       setSocketVariable = true;
     };
   };
+
+  nixpkgs = {
+    # You can add overlays here
+    overlays = [
+      # Add overlays your own flake exports (from overlays and pkgs dir):
+      outputs.overlays.nurPackages
+
+      # You can also add overlays exported from other flakes:
+      # neovim-nightly-overlay.overlays.default
+
+      # Or define it inline, for example:
+      # (final: prev: {
+      #   hi = final.hello.overrideAttrs (oldAttrs: {
+      #     patches = [ ./change-hello-to-hi.patch ];
+      #   });
+      # })
+    ];
+    # Configure your nixpkgs instance
+    config = {
+      # Disable if you don't want unfree packages
+      allowUnfree = true;
+    };
+  };
 }

flake.nix

@@ -18,9 +18,15 @@
       inputs.home-manager.follows = "home-manager";
     };
   };
-
-  outputs = { nixpkgs, home-manager, homeage, agenix, nur, ... }: {
+  
+  outputs = { self, nixpkgs, home-manager, homeage, agenix, nur, ... }:
+  let
+    inherit (self) outputs;
+  in
+  {
+    overlays = { nurPackages = nur.overlay; };
     nixosConfigurations.pim = nixpkgs.lib.nixosSystem {
+      specialArgs = { inherit outputs; };
       system =  "x86_64-linux";
       modules = [
         ./configuration.nix

home/default.nix

@@ -1,13 +1,10 @@
-{ pkgs, nur, ... }:
+{ pkgs, ... }:
 
-let
-  nur-no-pkgs = import (nur) { inherit pkgs; nurpkgs = pkgs; };
-in
 {
   imports = [
     ./bash
     ./neovim
-    (import ./firefox nur-no-pkgs) # TODO: bit of a hack, but better than before
+    ./firefox
     ./ssh
     ./syncthing
     ./alacritty

home/firefox/addons.nix

@@ -1,7 +1,7 @@
-{ nurpkgs, lib, ... }@args:
+pkgs: lib:
 let
-  rycee-addons = nurpkgs.repos.rycee.firefox-addons;
-  custom-addons = import ./custom-addons.nix args;
+  rycee-addons = pkgs.nur.repos.rycee.firefox-addons;
+  custom-addons = import ./custom-addons.nix pkgs lib;
 in
   {
     default = lib.concatLists [

home/firefox/custom-addons.nix

@@ -1,4 +1,4 @@
-{ pkgs, lib, ... }:
+pkgs: lib:
 let
   # Stolen from: https://github.com/nix-community/nur-combined/blob/master/repos/rycee/pkgs/firefox-addons/default.nix
   buildFirefoxXpiAddon = lib.makeOverridable ({ stdenv ? pkgs.stdenv, fetchurl ? pkgs.fetchurl,

home/firefox/default.nix

@@ -1,8 +1,7 @@
-nurpkgs:
-{ pkgs, lib, ... }@args:
+{ pkgs, lib, ... }:
 
 let
-  firefoxAddons = import ./addons.nix (args // { inherit nurpkgs; });
+  firefoxAddons = import ./addons.nix pkgs lib;
   firefoxSettings = {
     "browser.aboutConfig.showWarning" = false;
     "browser.toolbars.bookmarks.visibility" = "always";