runCommand -> error: output <path> is not allowed to refer to the following paths

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I’ve been using this in my configuration.nix to load firmware for my laptop:

  hardware.firmware = [
  (
    pkgs.runCommand "eve-firmware" { } ''
      mkdir -p $out/lib/firmware/intel
      cp -r ${./firmware/9d71-GOOGLE-EVEMAX-0-tplg.bin} "$out"/lib/firmware/
      cp -r ${./firmware/dsp_lib_dsm_core_spt_release.bin} "$out"/lib/firmware/
      cp -r ${./firmware/intel/dsp_fw_C75061F3-F2B2-4DCC-8F9F-82ABB4131E66.bin} "$out"/lib/firmware/intel
    ''
  )
  ];

This has been working fine until today when I updated my channel (nixos-23.05). Now when I sudo nixos-rebuild switch, I get:

error: output '/nix/store/yqia9kj5ymws739c72mrv208106y56s3-eve-firmware-xz' is not allowed to refer to the following paths:

         /nix/store/c7krn8qis1glqlmhw6h5691m980x4gmq-dsp_lib_dsm_core_spt_release.bin
         /nix/store/dr3x4lglrdpq912sdyjajimsk042iasj-dsp_fw_C75061F3-F2B2-4DCC-8F9F-82ABB4131E66.bin
         /nix/store/pww0p5vasmnx4gpfs1jaw3c6bp6is775-9d71-GOOGLE-EVEMAX-0-tplg.bin

I can see where this error is coming from in NixOS source, but it’s not clear to me how to fix it.