VBoxGuestAdditions.iso failing with vagrant

Hi,

I am trying alpine linux 3.4 with vagrant.

==> alpine-vm: Machine booted and ready!
[alpine-vm] No installation found.
The guest's platform ("alpine") is currently not supported, will try generic Linux method...
Copy iso file /usr/share/virtualbox/VBoxGuestAdditions.iso into the box /tmp/VBoxGuestAdditions.iso
mount: mounting /dev/loop0 on /mnt failed: Invalid argument

==> alpine-vm: Checking for guest additions in VM...
alpine-vm: No guest additions were detected on the base box for this VM! Guest
alpine-vm: additions are required for forwarded ports, shared folders, host only
alpine-vm: networking, and more. If SSH fails on this machine, please install
alpine-vm: the guest additions and repackage the box to continue.
alpine-vm:
alpine-vm: This is not an error message; everything may continue to work properly,
alpine-vm: in which case you may ignore this message.
The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!

mount /tmp/VBoxGuestAdditions.iso -o loop /mnt

Stdout from the command:

Stderr from the command:

mount: mounting /dev/loop0 on /mnt failed: Invalid argument

I have installed vagrant-alpine plugin and also follwed https://wiki.alpinelinux.org/wiki/VirtualBox_guest_additions
instructions. Am I missing something?

Thanks