In this paper I propose an analysis of the repairs of sonority sequencing violations in South Welsh in terms of a non-phonological process of stem allomorphy. As documented by Hannahs (2009), modern Welsh uses a variety of strategies to avoid word-final rising-sonority consonant clusters, depending in part on the number of syllables in the word. In particular, while some lexical items epenthesise a copy of the rightmost underlying vowel in the word, others delete one of the consonants in a cluster. In this paper, I argue that at least the deletion is not a live phonological process, and suggest viewing it as an instance of stem allomorphy in a stratal OT framework (Bermúdez-Otero 2013). This accounts for the lexical specificity of the pattern,which has been understated in the literature, and for the fact that cyclic misapplication of deletion and diachronic change are constrained by part-of-speech boundaries.