form_for fails for resources with no :index action

I declared a RESTful resource in my routes that only has :show, :new, and :create actions:

resources :foos, :only => [:show, :new, :create]

When I try to do a form_for(@foo), though, I get "undefined method 'foos_path' for #<Class>." This is because the resources call only creates a foos_path if the :index action is supplied.

I could, of course, simply define foos_path and foos_url, but I think resources should be smart enough to figure out to create those methods if :create is supplied.