# Updating The Build Plan

If you want to update the build plan for yourself. You can use these commands.

To update the nixpkgs base:

nix-prefetch-git https://github.com/NixOS/nixpkgs | tee nix/nixpkgs-src.json

To update the haskell.nix package set

nix-prefetch-git https://github.com/input-output-hk/haskell.nix | tee nix/haskell-nix-src.json

If you make modifications to the package.yaml or to the stack.yaml, you will need to run stack-to-nix using the haskell.nix tools.

stack-to-nix -o nix/ --stack-yaml stack.yaml

Remember, any modifications you make to the build plan will bring you out of lockstep with Shakebook’s official cache, at which point you may want to set up your own.