Search by ID?

Hi there,

I’m using acts_as_ferret in RoR and I have a tiny problem that I don’t

Sometimes I want to search by the ID of my models, but if I enter a
model id it never gets found. I tried putting :id in the field list, but
it threw and error saying that it is already indexed. How do I tell
acts_as_ferret that I’d like to search by id as well as everything else?