sed error on Chimera Linux, likely due to different userland

[fusion809]

A distro that I feel could benefit from this tool more than most is Chimera Linux as I have found it particularly easy to break a Chimera Linux install. I downloaded the tar.gz of commit b509fca, decompressed it, cd'ed into the directory and ran make install it returned this error:

I have gawk, bash, btrfs-progs and grub installed. I think the problem here is that Chimera uses FreeBSD's userland. Is it possible that this line could be modified to work with FreeBSD's userland?