OpenSSL issue when building Rust workspace with crane

Help
1

I’m attempting to build a Rust workspace that depends on the openssl-sys crate using this flake:

{
  description = "tf2ultimate";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";

    crane.url = "github:ipetkov/crane";

    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, crane, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};

        inherit (pkgs) lib;

        craneLib = crane.mkLib pkgs;

        tf2ultimate-apps = craneLib.buildPackage {
            buildInputs = with pkgs; [ dbus openssl ];
            nativeBuildInputs = with pkgs; [ pkg-config ];
            src = lib.fileset.toSource {
                root = ./.;
                fileset = lib.fileset.unions [
                    ./Cargo.toml
                    ./Cargo.lock
                    ./backpacktf-common
                    ./backpacktf-listing-freshener
                    ./backpacktf-ws-db-writer
                    ./stntrading-api
                    ./stntrading-listing-freshener
                    ./tf2-db-common
                    ./tf2-db-migrator
                    ./tf2-schema
                    ./tf2-schema-updater
                ];
            };
        };
      in
      {
        packages.tf2ultimate = tf2ultimate-apps;
      });
}

However, when trying to build the flake I get this error:

The system library `openssl` required by crate `openssl-sys` was not found.
The file `openssl.pc` needs to be installed and the PKG_CONFIG_PATH environment variable must contain its parent dir>
PKG_CONFIG_PATH contains the following:
    - /nix/store/yv8ksqj4pmpxcq8878hn07nirh6mn5d4-zstd-1.5.6-dev/lib/pkgconfig
    - /nix/store/qj94g4g6i5z2m99pfjvjgwgqx0vy216q-dbus-1.14.10-dev/lib/pkgconfig
    - /nix/store/cyccwyjsfqkg5p2k096wvd274nv80q0l-expat-2.6.2-dev/lib/pkgconfig

HINT: you may need to install a package such as openssl, openssl-dev or openssl-devel.

After researching other cases of similar problems, I have tried setting PKG_CONFIG_PATH="${pkgs.openssl.dev}/lib/pkgconfig", as well as setting OPENSSL_DIR="${pkgs.openssl.dev}", to no avail.

Is there something else I’m missing? Any help would be appreciated, thank you!