The Carter–Leslie doomsday argument,1 as standardly presented, relies on the assumption that you have knowledge of your approximate birth rank. I shall demonstrate that the doomsday argument can still be given in a situation where you have no knowledge of your birth rank. As I shall show, this allows one to reply to Bostrom’s2 defence of the doomsday argument against the refutations given by Dieks, Kopf et al., Bartha and Hitchcock, and Olum.3 (I shall call this refutation ‘Dieks’ reply’ for short.) The doomsday argument runs as follows. Suppose you have narrowed the possibilities for doom down to two: