Haitian, a French-lexifier creole with a Gbe substrate, shows an asymmetry in the way it has adapted French liquids: the French lateral was maintained in postvocalic coda position in Haitian, but the French rhotic was systematically deleted in this position. This paper presents the results of a perception study showing that the lateral is generally more perceptible than the rhotic in coda position in Modern French. The hypothesis that perception played a role in the phonological asymmetry in Haitian is compatible with these results. The paper sketches an analysis of how the perceptual asymmetry between French coda laterals and rhotics resulted in the emergence of a new phonological grammar, distinct from both the grammar of the substrate and superstrate languages. This analysis is in line with previous works on the role of perception in second language acquisition, loanword adaptation, creolization, and sound change more generally.