Historical accounts of biological are thought to have, as a point in their favour, their being able to accommodate malfunction. Recently, this has been brought into doubt by Paul Sheldon Davies’s argument for the claim that both selected malfunction (that of the selected functions account) and weak etiological malfunction (that of the weak etiological account), are impossible. In this paper I suggest that in light of Davies’s objection, historical accounts of biological function need to be adjusted to accommodate malfunction. I propose a historical account which places two conditions on membership of a functional kind. My claim is that it is in virtue of a trait’s meeting these conditions that it is a member of a functional kind, and can thus malfunction. I suggest that a version of my proposal can be adopted by both the selected effects and weak etiological theorists, and so conclude that such a proposal meets Davies’s objection.