Unable to rebuild after invalid --profile-name option

After trying to rebuild my system with the profile name “iwlwifi: disable 802.11n, hwcrypto” nixos-rebuild switch fails with

building Nix...
building the system configuration...
Traceback (most recent call last):
  File "/nix/store/3rs84anh60r4zw4y7v9zxmz33z2ady8s-systemd-boot-builder.py", line 240, in <module>
  File "/nix/store/3rs84anh60r4zw4y7v9zxmz33z2ady8s-systemd-boot-builder.py", line 209, in main
    write_entry(*gen, machine_id)
  File "/nix/store/3rs84anh60r4zw4y7v9zxmz33z2ady8s-systemd-boot-builder.py", line 108, in write_entry
    with open(tmp_path, 'w') as f:
OSError: [Errno 22] Invalid argument: '/boot/loader/entries/nixos-iwlwifi: disable 802.11n, hwcrypto-generation-1.conf.tmp'
warning: error(s) occurred while switching to the new configuration

The error persists without the --profile-name option and after a reboot. Is there some temporary file (that survives reboots) that must be removed to fix this? /boot/loader/entries contains no entries matching the profile name.

Got some help over on the IRC: my /boot is formatted as fat32 on which : is an invalid character for files; removing the entries containing it in /nix/var/nix/profiles/system-profiles/ enabled me to rebuild my system again.