Mauritian Creole displays an alternation between a short and a long form of the verb, which is reminiscent of the conjoint–disjoint alternation found in some eastern Bantu languages. Based on comparison with other French-based creoles and socio-historical evidence, we conclude that the Bantu substrate must have had an impact on the grammatical system of Mauritian Creole. We compare the synchronic properties of the alternations in Mauritian Creole and the most likely substrate Bantu languages of northern Mozambique and examine two possible scenarios for the influence of Bantu on the Mauritian verbal alternation, concluding that probably only the (syntactic) basics of the Bantu alternation motivated the persistence of the alternation in Mauritian Creole.