Phonological alternations often happen to conform to phonotactic regularities, from which a single mechanism for phonotactics and alternations has been claimed. We note, however, that empirical evidence supporting the link between phonotactics and alternations comes only from English native speakers whose first language (L1) does exhibit phonotactically motivated alternation patterns. This article examines whether the link between phonotactics and alternations is universally available. To do so, we test learning of phonotactics and alternations with Cantonese native speakers, whose L1 provides no evidence for or against the link. We address learning of a vowel harmony pattern through the use of three artificial languages; one with a harmony pattern both within and across stems, another with a harmony pattern only across stems; and the other with a disharmony pattern within stems but harmony across stems. Learners successfully acquired harmony phonotactics according to input patterns, but they showed no difference in learning alternation patterns across the three languages. Our results suggest that the link between phonotactics and alternations might be language-specific: Only upon receiving L1 evidence, learners can use a unified mechanism to encode phonotactics and alternations.