Frans, I ran /bin/archdetect on both my system and my MiniMac and in both cases got: i386/generic So it appears even on the Mac that /lib/partman/lib/disk-label.sh doesn't take the Mac path in: i386) case "$sub" in mac) echo gpt;; *) echo msdos;; Perhaps this was different on the older Intel Macs without the CSM BIOS. So it seems I need to look at archdetect now. Just FYI. Charles.