Hello Florian & Thomas, I was able to reproduce the issue: ‘guix system disk-image --file-system-format=iso9660’ would create partly unreadable images. Since this was pretty much like the issue I had encountered with ‘guix system docker-image’, which would produce truncated tarballs, and since calling ‘sync’ wasn’t enough, I looked at our file system mount options… The attached patch fixes the problem for me. In hindsight, it’s not surprising that “cache=loose” on the /xchg mount point (used to exchange data between the host and the guest) would have this effect. Florian, it would be great if you could confirm. Just apply it on ‘master’, and then run: ./pre-inst-env guix system disk-image --file-system-format=iso9660 \ gnu/system/install.scm Thanks, and apologies for blaming Xorriso, which presumably never had anything to do with it! Ludo’.