According to epistemic deontologism, attributions of epistemic justification are deontic claims about what we ought to believe. One of the most prominent objections to this conception, due mainly to William P. Alston, is that the principle that ‘ought’ implies ‘can’ rules out deontologism because our beliefs are not under our voluntary control. In this paper, I offer a partial defense of Alston’s critique of deontologism. While Alston is right that OIC rules out epistemic deontologism, appealing to doxastic involuntarism is not necessary for generating that tension. Deontologists would still have a problem with OIC if doxastic voluntarism turned out to be true or if deontologism did not require voluntarism. This is because, in short, epistemic justification does not imply ‘can’. If, as deontologists maintain, epistemic justification implies ‘oughts’, then epistemic justification must also imply ‘can’ given OIC. But since epistemic justification does not imply ‘can’, OIC dictates that we reject deontologism. I end by exploring the possible consequences of this incompatibility between OIC and deontologism. My conclusion is that at least one of the following claims must be true. Either ‘ought’ does not imply ‘can’, attributions of epistemic justification are not deontic claims, or epistemic claims lack necessary or categorical normative authority.