building memstick without root

hello,

is it expected that running 'make -C release memstick' requires root?
the build fails for me with:

install: /src/obj/src/freebsd/src/main/riscv.riscv64/release/dist/kernel/boot/kernel/kernel: chown/chgrp: Operation not permitted

as i understand it, makefs should be able to build images as a non-root
user using mtree, but i'm not sure if this is hooked up to the build
system, or if i'm doing something else wrong - maybe i need a
make.conf/src.conf option set?