diff --git a/README.md b/README.md
index 4391186..4eb18ac 100644
--- a/README.md
+++ b/README.md
@@ -144,7 +144,6 @@ processors work just fine (even for macOS Sonoma).
 
   Choose a product to download (1-9): 7
   ```
-
   Note: Modern NVIDIA GPUs are supported on HighSierra but not on later
   versions of macOS.
 
@@ -164,6 +163,14 @@ processors work just fine (even for macOS Sonoma).
 
   NOTE: Create this HDD image file on a fast SSD/NVMe disk for best results.
 
+* Or use a simple nix command if you have it installed.
+
+  ```
+  nix run github:kholia/OSX-KVM/ --no-write-lock-file -- catalina
+  ```
+  This will clone a repository at `./OSX-KVM`, download the image,
+  give everything the right permissions, and start `./OpenCore-Boot.sh`.
+
 * Now you are ready to install macOS 🚀
 
 
diff --git a/flake.nix b/flake.nix
index d8247bb..e2b8db1 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,5 +1,5 @@
 {
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/24.05";
+  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
 
   inputs.flake-utils.url = "github:numtide/flake-utils";
 
@@ -13,6 +13,12 @@
       system:
       let
         pkgs = nixpkgs.legacyPackages.${system};
+        src = pkgs.fetchFromGitHub {
+          owner = "kholia";
+          repo = "OSX-KVM";
+          rev = "master";
+          hash = "sha256-kxhVe3U2lFt6joSMUGWZuHOfFHdzwKXP4H3hz/cA2vE=";
+        };
       in
       {
         devShells.default = pkgs.mkShell {
@@ -22,7 +28,21 @@
             qemu_kvm
           ];
         };
+        apps.default = {
+          type = "app";
+          program = toString (pkgs.writeShellScript "build-osx" ''
+            name=$1
+            ${pkgs.coreutils}/bin/mkdir ./OSX-KVM 
+            ${pkgs.coreutils}/bin/cp -r --no-preserve=mode ${src}/* ./OSX-KVM
+            ${pkgs.coreutils}/bin/chmod -R +w ./OSX-KVM
+            ${pkgs.coreutils}/bin/chmod -R +x ./OSX-KVM/*.sh
+            cd ./OSX-KVM
+            ${pkgs.python3}/bin/python3 ./fetch-macOS-v2.py --shortname=$name
+            ${pkgs.dmg2img}/bin/dmg2img -i BaseSystem.dmg ./BaseSystem.img
+            ${pkgs.qemu}/bin/qemu-img create -f qcow2 ./mac_hdd_ng.img 256G
+            ./OpenCore-Boot.sh
+          '');
+        };
       }
     );
 }
-