Guest Agent get-fsinfo doesn't show ZFS volumes

Calling get-fsinfo on a virtual machine does not include ZFS volumes. Calling on a system with a single ZFS disk (ZFS as root fs) simply returns '[]', if other disks exist on the guest it only shows these.

Expected behaviour: Show file system details like with other fs formats.

Tried with debian stretch default qemu-guest-agent package and v4.0.0 from git, compiled locally - result is the same.
Host is using QEMU 3.0.1, but that shouldn't matter, right?