{
  description = "Overlay for a policy-configurable non-ESR Firefox";

  inputs.nixpkgs.url = "github:NixOS/nixpkgs/491072e797f6d28960f182d45125f1f93b9522ce";
  # inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

  outputs = { self, nixpkgs }: let
    pkgs = import nixpkgs { system = "x86_64-linux"; };
  in rec {
    packages.x86_64-linux = rec {
      default = firefox-patched-unwrapped;

      firefox-patched-unwrapped = (pkgs.firefox-unwrapped.override {
        geolocationSupport = false;
        googleAPISupport = false;
        drmSupport = false;

        requireSigning = false;
        allowAddonSideload = true;
      }).overrideAttrs (oldAttrs: rec {
        patches = oldAttrs.patches ++ [
          # I want to preconfigure the search engine settings to make
          # DuckDuckGo the default search engine and remove most of the
          # others.  For some reason, Mozilla is scared of allowing
          # managed policies to set the default search engine in non-ESR
          # firefox.  This is a two-line patch to remove that
          # restriction.
          # https://github.com/mozilla/policy-templates/issues/484
          ./allow-searchengines-policy.patch
        ];
      });
    };

    overlay = final: prev: {
      inherit (packages.x86_64-linux) firefox-patched-unwrapped;
    };
  };
}