This article examines whether the legal assessment of killings under international humanitarian law (IHL) bears upon the determination of genocide by killing members of a protected group under Article II(a) of the Genocide Convention. While the Convention applies equally in time of peace and war, not all killings in armed conflict are prohibited under the rules of IHL governing hostilities. This raises the question whether, in the context of an armed conflict, only unlawful killings under IHL may qualify as underlying acts of genocide, or whether the notion of ‘killing’ under Article II(a) remains autonomous from its qualification under the IHL. This article moves from the position of the International Court of Justice in the Croatia v. Serbia genocide case, where the Court appears to suggest that killings of members of the protected group resulting from attacks not deliberately directed against civilians may fall outside the scope of Article II(a). It argues that this approach risks introducing an IHL-based filter into the definition of genocide and conflates intentional killing and the IHL prohibition of deliberate attacks against civilians. It further examines the two possible theoretical premises underpinning this approach and demonstrates that neither provides a convincing basis for it. This article further demonstrates that conditioning the identification of the underlying acts of genocide upon their prior assessment under IHL entails systemic consequences. It risks fragmenting the application of the prohibition of genocide depending on the applicable IHL framework, in light of the differences between international and non-international armed conflicts. It also risks displacing the central element of genocide — namely, the intent to destroy a protected group — by shifting the analytical focus from the purpose of the conduct to its classification under IHL. This article concludes that the prohibition of genocide retains an autonomous normative function, centred on the protection of groups as such, which cannot be subordinated to the regulatory logic of IHL.