{ overlays ? true }:
let
  nixpkgs-pin = {
    name = "nixpkgs";
    url = "https://github.com/NixOS/nixpkgs-channels/archive/353333ef340952c05332e3c271dff953264cb017.tar.gz";
    sha256 = "sha256:0bv34yz892yxhx2kb8a1yr5pm0g8ck5w021yj87r7kfnp416apdh";
    };

  nixpkgs-src = builtins.fetchTarball nixpkgs-pin;
  args =
    if overlays
    then { overlays = [ (import <psio/nixos/openssl-111k.nix>) ]; }
    else { };
  nixpkgs = import nixpkgs-src args;
in
  nixpkgs