Mbaham and Iha are two closely related Papuan languages spoken on the Onin Peninsula in Northwest Bomberai, New Guinea. The prominent position of Onin in the seascape of the region means that groups in Onin were almost certainly involved in the formation of the Wallacean Linguistic Area. Applying the comparative method, we present a reconstruction of the lexicon of their common ancestor, proto-Mbaham-Iha, and identify Austronesian lexical influences on them. This work represents a small but important first step towards understanding the position of these languages of Onin within Linguistic Wallacea.