Má go, maga, maha go ‘if not, unless’. Confusion of prepositions ach and amach ó ‘except’ spread to conjunction ach go, hence amach ó go (= má go), from which Ros Guill preposition amach ach was extracted based on homophony of ach and ó in this dialect as /a/. Cf. B. Ó Buachalla, in Ériu 23 (1972), pp. 143-161.