Trouble specifying file: option for config.vm.disk for disk, still creates a new one

I am trying to mount an existing disk (vdi) to be used with a box. I specified the following below but it says “default: Disk ‘home’ not found in guest. Creating and attaching disk to guest…” creates a new one. Any ideas?

Vagrant 2.2.18

config.vm.disk :disk, name: “home”, size: “100GB”, file: “./home.vdi”