|Abstract:||The postposed definite determiner (DET) in French-lexified Antillean Creoles such as Haitian and St. Lucian displays an unexpected pattern of allomorphy. Its C-initial form 'la' appears after consonant- and glide-final stems ('pitit la' 'the child') whereas a vocoid-initial form appears after stems ending in vowels. Glides are inserted after non-low vowels ('ru wa' 'the wheel'), but a is used after low vowels resulting in vowel hiatus as in 'papa a' 'the father'. Syllable markedness as conceived of in standard OT would predict a preference for CV sequences throughout instead of the observed pattern involving consonant clusters and vowel hiatus. This challenge to conventional OT is addressed exploring the model of Lexical Representation as Pure Markedness (LRPM) developed in Klein (2000), based on Golston (1996). In LRPM, violations of constraints serve to encode inputs. Such lexical constraint violations are kept track of through faithfulness constraints. Outputs which do not respect input constraint violations may be suboptimal through the faithfulness violation. Thus, this model is able to encode morpholexical idiosyncrasies by using only constraints and constraint violations and without increasing the overall number of constraints.