This paper investigates the syntax of kena adversative passives in Malay. First, we establish the relation between kena passives and sentences with kena meaning 'have to' as a passive-active pair. These two constructions have been considered unrelated. A close examination of kena passive sentences in relation to their active counterparts reveals that kena is actually not a passive marker but a member of a class of predicates giving rise to funny control, a phenomenon whereby the external argument of these predicates is associated with either the internal or the external argument of the passive clause they embed. This enables a principled syntactic explanation for why kena is used in the two relevant constructions. We argue that voice, both active and passive, is indicated covertly in kena sentences when the lower verb bears no morphological voice marker. It is suggested that "covert voice alternation" is one of the typologically common voice alternations, and it enables us to understand the seemingly manifold voice systems of Austronesian languages in the Malay Archipelago in a more connected manner.