This paper presents phonological processes in Xitsonga diminutives. The round vowels /u/ and /o/ are changed into the glide [w] to avoid vowel hiatus. When the glide [w] is preceded by labial consonants, then other processes occur: either the labial nasal [m] corresponds to a velar, or the glide [w] deletes when preceded by labial obstruents. The seemingly disjunctive processes are argued to be responses to the OCP-LABIAL constraint in which adjacent segments with [labial] are prohibited. A rule-based analysis and a constraint-based (Optimality Theory) analysis are presented to discuss these processes. Data with affrication is introduced as an alternative repair strategy, but is not included in the formal analysis, which focuses on labial d...