Adjectival syllable count, often used to predict English comparatives more versus -er, is of little help in predicting the comparatives of adjectives ending in <y>, pronounced /i/, here called the y-adjectives. Examples of y-adjectives include silly and worthy. This article considers whether the phonemic segment count (segment count) and penultimate syllable weight (penultimate weight) of y-adjectives may serve as alternatives to syllable count in predicting more versus -er. The segment count and penultimate weight of relevant y-adjective tokens from a set of diachronic corpora are studied, alongside the tokens’ morphological complexity and period of occurrence in two separate, parallel sets of mixed-effects models. Syllabification principles for penultimate weight coding differentiate the two sets of modelling. Findings converge on segment count as a predictor of the comparative form, while the role of morphological complexity remains less clear, emerging significantly from one set of modelling but not the other. A rethinking of adjectival length based on segment count is advanced for our understanding of y-adjective comparatives. Discussed also are downstream implications of variant syllabification theories on accounts of y-adjective comparatives, together with insights shed on morphophonological intersections and the potential place of English y-adjective comparatives within the ambit of English alternations.