A dispreference for onsetless syllables is often manifested by processes of consonant insertion or vowel deletion which eliminate onsetless syllables, and it is sometimes manifested by disallowing prosodic distinctions which onsetful syllables make, e.g. onsetless syllables may resist bearing tone or stress. This paper investigates the interaction between minimality and the structure of onsetless syllables in the Bantu language Zinza, documenting a previously unobserved onsetless effect which is partially conditioned by minimality. In Zinza, word-initial vowels of disyllables are lengthened, so /o-ljá/ becomes [óó-lja] ‘you eat’ (compare [o-líma] ‘you cultivate’ and [bá-lja] ‘they eat’, with no lengthening). These facts test previous theories of onsetless effects (Downing 1993, 1998, Odden 1995, Orie 2000). I argue that a special representation of onsetless syllables is not warranted, and does not explain this pattern of lengthening. A constraint against word-initial short onsetless syllables interacting with word minimality suffices to explain this lengthening.