diff --git a/base.nix b/base.nix
index e7f5d6d..093d1fc 100644
--- a/base.nix
+++ b/base.nix
@@ -39,6 +39,22 @@ with lib;
         The set of NTP servers from which to synchronise.
       '';
     };
+    system.systemBuilderArgs = mkOption {
+      type = types.attrsOf types.unspecified;
+      internal = true;
+      default = {};
+      description = lib.mdDoc ''
+        `lib.mkDerivation` attributes that will be passed to the top level system builder.
+      '';
+    };
+    system.systemBuilderCommands = mkOption {
+      type = types.lines;
+      internal = true;
+      default = "";
+      description = ''
+        This code will be added to the builder creating the system store path.
+      '';
+    };
   };
   config = {
     environment.systemPackages = lib.optional config.not-os.nix pkgs.nix;
diff --git a/default.nix b/default.nix
index d5e1e2d..0812645 100644
--- a/default.nix
+++ b/default.nix
@@ -1,12 +1,26 @@
-{ configuration ? import ./configuration.nix, nixpkgs ? <nixpkgs>, extraModules ? [], system ? builtins.currentSystem, platform ? null }:
+{ configuration ? import ./configuration.nix
+, nixpkgs ? <nixpkgs>
+, extraModules ? []
+, system ? builtins.currentSystem
+, platform ? null
+, crossSystem ? null }:
 
 let
   pkgs = import nixpkgs { inherit system; platform = platform; config = {}; };
-  pkgsModule = rec {
+  pkgsModule = {config, ... }: {
     _file = ./default.nix;
-    key = _file;
+    key = ./default.nix;
     config = {
-      nixpkgs.localSystem = { inherit system; };
+      nixpkgs.pkgs = (import nixpkgs {
+        inherit system;
+        #crossSystem = (import <nixpkgs/lib>).systems.examples.aarch64-multiplatform;
+        config = config.nixpkgs.config;
+      });
+      nixpkgs.localSystem = {
+        inherit system;
+      } // pkgs.lib.optionalAttrs (crossSystem != null) {
+        inherit crossSystem;
+      };
     };
   };
   baseModules = [
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..4561661
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,42 @@
+{
+  "nodes": {
+    "firmware": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1697732010,
+        "narHash": "sha256-kGXbqkqHCPU2Xz6az3LtdAccVzGtlq+vnTLiR3Xl9+8=",
+        "owner": "raspberrypi",
+        "repo": "firmware",
+        "rev": "ce3a0b4197eaf311ba0734efdb9f5bdedefe5e27",
+        "type": "github"
+      },
+      "original": {
+        "owner": "raspberrypi",
+        "repo": "firmware",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1697730408,
+        "narHash": "sha256-Ww//zzukdTrwTrCUkaJA/NsaLEfUfQpWZXBdXBYfhak=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "ff0a5a776b56e0ca32d47a4a47695452ec7f7d80",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "firmware": "firmware",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..1a9000b
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,23 @@
+{
+  inputs = {
+    firmware = {
+      url = "github:raspberrypi/firmware";
+      flake = false;
+    };
+  };
+  outputs = { self, nixpkgs, firmware }: {
+    packages.armv7l-linux = let
+      platforms = (import nixpkgs { config = {}; }).platforms;
+    in {
+      rpi_image = (import ./default.nix {
+        extraModules = [
+          ./rpi_image.nix
+          { system.build.rpi_firmware = firmware; }
+        ];
+        platform = system: platforms.raspberrypi2;
+        system = "armv7l-linux";
+        inherit nixpkgs;
+      }).config.system.build.rpi_image;
+    };
+  };
+}
diff --git a/rpi_image.nix b/rpi_image.nix
index de8873a..ef1903e 100644
--- a/rpi_image.nix
+++ b/rpi_image.nix
@@ -11,6 +11,7 @@
     cmdline = pkgs.writeText "cmdline.txt" ''
       console=ttyS0,115200 pi3-disable-bt kgdboc=ttyS0,115200 systemConfig=${builtins.unsafeDiscardStringContext config.system.build.toplevel} netroot=192.168.2.1=9080d9b6/root.squashfs quiet splash plymouth.ignore-serial-consoles plymouth.ignore-udev
     '';
+    firm = config.system.build.rpi_firmware;
   in pkgs.runCommand "rpi_image" {} ''
     mkdir $out
     cd $out
@@ -18,10 +19,10 @@
     cp ${cmdline} cmdline.txt
     cp -s ${config.system.build.kernel}/*zImage kernel7.img
     cp -s ${config.system.build.squashfs} root.squashfs
-    cp ${./../bcm2710-rpi-3-b.dtb} bcm2710-rpi-3-b.dtb
-    cp -r ${./../../overlays} overlays
-    cp -s ${../../start.elf} start.elf
-    cp ${../../fixup.dat} fixup.dat
+    cp ${firm}/boot/bcm2710-rpi-3-b.dtb bcm2710-rpi-3-b.dtb
+    cp -r ${firm}/boot/overlays overlays
+    cp -s ${firm}/boot/start.elf start.elf
+    cp ${firm}/boot/fixup.dat fixup.dat
     cp -s ${config.system.build.initialRamdisk}/initrd initrd
     ls -ltrhL
   '';