Nested Forms with has_many associations with validations

I want to have a parent model that I can add child objects (via a
has_many association) using the rails 2.3 nested form syntax. However,
it seems like rails throws an error during validation of the parent
model if I have a validates_presence_of :parent_id defined in the child
model.

Is the only solution to this to remove the validates_presence_of
:parent_id? This seems like a hack-ish workaround.