Many Turkic languages, including Kyrgyz, restrict sonorant onsets depending on the preceding context. Sonorant onsets often alternate with obstruent counterparts in a process known as desonorization: for example, the /l/ in /dan-lar/ 'pieces' desonorizes to [d] in the output form [dan-dar]. All previous accounts of this phenomenon have attributed this to the syllable contact law (Murray & Vennemann, 1983), a hypothesis favoring falling sonority and disfavoring rising sonority in cross-syllabic consonant clusters. However, Turkic desonorization presents a challenge for the syllable contact law. I examine the details of the pattern for Kyrgyz, and propose an account for it based on the Licensing By Cue framework (Steriade, 1997), in which perceptual information about the distinctiveness of contrasts is encoded as constraints in the grammar. I show that languages which restrict sonorants after a syllable boundary also restrict them word-initially, a pattern not accounted for under the syllable contact law, but predicted by my account. In addition, I show that a syllable contact law-based approach wrongly predicts that different segments should pattern together in desonorization, whereas my account predicts that they pattern independently, a prediction borne out by a cross-linguistic survey of patterns across different Turkic languages.