has_many and belongs_to associations in factory_girl

I have these models that I'm trying to create factories for using factory_girl.

class Foo < ActiveRecord::Base
  belongs_to :baz
end

class Baz < ActiveRecord::Base
  has_many :foos
end

I'm not sure how to create the factories without creating a loop where the factories endlessly call each other.

Factory.define :foo do |f|
  f.after_create do |ff|
    ff.baz = Factory(:baz)
  end
end

Factory.define :baz do |f|
  f.after_create do |ff|
    ff.foos = [Factory.create(:foo)]
  end
end

I realize I can just leave out ff.foos = [Factory.create(:foo)] in the baz factory, but then in my baz tests I'm forced to used foo.baz instead of just using baz. Am I forced to use the baz object by fetching it out of a foo factory in my tests? Or is there a better way?