+## Nix
+
+If you're on [NixOS](https://nixos.org/), or have Nix installed on Linux or macOS, run `nix-shell` from the repository root to get a build environment.
+
+By default, this will download compilers for both AVR and ARM. If you don't need both, disable the `avr` or `arm` arguments, e.g.:
+
+ nix-shell --arg arm false
+
+## macOS