polymorphic associations wrong when used with inherited class?

Consider the following:

class Event
  belongs_to :event_object, :polymorphic => true
end

class Asset < ActiveRecord::Base
end

class EventedAsset < Asset
  has_one :event, :as => :event_object
end

EventedAsset.find(:first).event generates the following SQL:

SELECT * FROM `events` WHERE (events.event_object_id = 1 AND
events.event_object_type = 'Asset') LIMIT 1

shouldn't this be:

SELECT * FROM `events` WHERE (events.event_object_id = 1 AND
events.event_object_type = 'EventedAsset') LIMIT 1

I guess i should RTFM.

(here for anyone with the same problem:
http://api.rubyonrails.com/classes/ActiveRecord/Associations/ClassMethods.html)

Still, IMO, you shouldn't have to define a crazy method like:

def attachable_type=(sType)
  super(sType.to_s.classify.constantize.base_class.to_s)
end

to make STI work with polymorphic associations, it should "just work,"
like everything else does in rails.