A common objection to unconditional basic income is that it is unfair because it allows people to live off the labour of their fellow citizens without making a reciprocal productive contribution to society (the 'exploitation objection'). The paper outlines four responses to the objection: the perfectionism, balance of fairness, balance of reciprocity, and inherited asset responses. While it finds little merit in the first, it argues that, taken together, the latter three add up to a powerful reply to the exploitation objection. In concluding, the paper also explains that even if the exploitation objection can be satisfactorily met, there might still be other justice-based reasons for making basic income conditional on behaviour.