Nix tricks: lock nixpkgs to the version of your system [nix/trick-lock-current]

With NixOS:

nix flake lock --override-input nixpkgs github:NixOS/nixpkgs/$(nixos-version --hash)

With nix-darwin:

nix flake lock --override-input nixpkgs github:NixOS/nixpkgs/$(darwin-version --nixpkgs-revision)