Nix To get a devshell hooked into a recent version of Rust, you add the overlay into your flake.nix file. # ... inputs.mozilla-overlay = { type = "github"; owner = "mozilla"; repo = "nixpkgs-mozilla"; flake = false; }; outputs = { self, nixpkgs, mozilla-overlay, flake-utils, devshell }: # make sure mozilla-overlay is in the inputs overlays = [ (import mozilla-overlay) # add it into the overlay. The ()'s around it make it into a function, which is required for overlays. devshell.overlay self.overlay ];