Utopian literature has a vexed relationship with disability. Literary utopias have frequently been informed by eugenic models of perfection in which 'utopia' is defined as the absence of disability. This eugenic utopian tradition uses the figure of the implicitly able, 'perfect' child to represent the future, while simultaneously prohibiting the reproduction of disabled and otherwise 'imperfect' children, figured as waste. In this article, I critique the influence of eugenics, and specifically of this dual conceptualisation of childhood, on utopianism. To this end, I engage with disability justice activist Mia Mingus' short story 'Hollow' (2015). In 'Hollow' a group of disabled activists known as the UnPerfects have been shipped off-world to an uninhabited planet turned prison camp. By imagining her characters revolting against their guards and attempting to build a utopian society, Mingus succeeds in critiquing eugenic utopianism while maintaining a commitment to radical transformation. I argue that this radical transformation can be usefully connected, not only to disability justice, but to the interlinked projects of children's liberation and critical utopianism. 'Hollow' offers an example of a text which refuses to position either childhood or utopia in an ever-receding future, instead making an UnPerfect, disabled, child-centric utopia of the present thinkable.