diff --git a/dist.nix b/dist.nix
index 460be41..d5e2367 100644
--- a/dist.nix
+++ b/dist.nix
@@ -1,10 +1,8 @@
-{ pkgs ? import <nixpkgs> { inherit system; }, system ? builtins.currentSystem
-, financierVersion }:
+{ pkgs, system, stdenv, financierVersion }:
 
-let
-  financier = (import ./default.nix { inherit pkgs system; }).package;
+let financier = (import ./default.nix { inherit pkgs system; }).package;
 
-in pkgs.stdenv.mkDerivation {
+in stdenv.mkDerivation {
   version = financierVersion;
   pname = "financier-dist";
   src = "${financier}/lib/node_modules/financier";
diff --git a/flake.nix b/flake.nix
index cfa89f9..90b167e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -10,21 +10,13 @@
       financierVersion = (builtins.fromJSON
         (builtins.readFile "${inputs.financier}/package.json")).version;
       nodeVersion = "12";
-
-      overlay = final: prev: {
-        financier-dist = import ./dist.nix {
-          inherit financierVersion;
-          inherit (prev) pkgs system;
-        };
-      };
     in inputs.flake-utils.lib.eachDefaultSystem (system:
-      let
-        pkgs = import nixpkgs {
-          inherit system;
-          overlays = [ overlay ];
-        };
+      let pkgs = import nixpkgs { inherit system; };
       in {
-        packages = { inherit (pkgs) financier-dist; };
+        packages = {
+          financier-dist =
+            pkgs.callPackage ./dist.nix { inherit financierVersion; };
+        };
         defaultPackage = self.packages.${system}.financier-dist;
         devShell = pkgs.mkShell {
           packages = with pkgs; [ nodePackages.node2nix ];
@@ -34,10 +26,10 @@
           '';
         };
       }) // {
-        inherit overlay;
-        nixosModule = {
+        nixosModule = { pkgs, lib, ... }: {
           imports = [ ./module.nix ];
-          nixpkgs.overlays = [ self.overlay ];
+          services.financier.package =
+            lib.mkDefault self.packages.${pkgs.system}.financier-dist;
         };
       };
 }
diff --git a/module.nix b/module.nix
index cea1162..162ce4f 100644
--- a/module.nix
+++ b/module.nix
@@ -1,8 +1,6 @@
 { config, lib, pkgs, system, ... }:
 with lib;
-let
-  inherit (pkgs) financier-dist;
-  cfg = config.services.financier;
+let cfg = config.services.financier;
 in {
   imports = [ ];
 
@@ -17,6 +15,13 @@ in {
       example = "example.org";
     };
 
+    package = mkOption {
+      type = types.package;
+      description = ''
+        Financier package to use.
+      '';
+    };
+
     server = mkOption {
       type = types.enum [ "nginx" "caddy" ];
       description = ''
@@ -37,7 +42,7 @@ in {
       virtualHosts."${cfg.hostName}" = {
         forceSSL = true;
         enableACME = true;
-        root = financier-dist;
+        root = cfg.package;
         locations."/".tryFiles = "$uri $uri/ /index.html";
       };
     };
@@ -47,7 +52,7 @@ in {
 
       config = ''
         ${cfg.hostName} {
-          root * ${financier-dist}
+          root * ${cfg.package}
           file_server
           try_files {path} {path}/ /index.html
         }