The aspect prefix /n-/ in Comalapa Kaqchikel (Mayan) surfaces with a following [t] or [d] when attaching to monosyllabic, vowel-initial verbs. We refer to this process as 'nasal hardening', and argue that it emerges from constraints barring affixal material from positions of phonological prominence; these constraints team-up with phonetically- grounded constraints on onset sonority and place licensing to produce [t]~[d] epenthesis. The analysis is supported by allophonic evidence which identifies stressed syllables and word-initial syllables as 'strong' positions in Kaqchikel and other K'ichean-branch Mayan languages. Curiously, the oral stop [d] which results from nasal hardening is otherwise quite rare in Mayan languages. We deal with with the oddity of finding [d] in this context by means of The Emergence Of The Unmarked: certain constraints on [NC] clusters become crucially active only in contexts of epenthesis, when IO-Faithfulness is rendered inert. The paper closes with some discussion of the historical development of these patterns across dialects of Kaqchikel.