The way Bua languages express number on nouns mostly consists of alternating suffixes that bear witness of a former classifi cation system. However, Kulaal is the only present-day language where these markers are not frozen but actually trigger agreement with free, optional determiners that follow the noun and may show some formal affi nity with its suffix. For several reasons, previous attempts at reconstructing a historical noun morphology common to all Bua languages considered the sole suffi xes and neglected the determiners present in Kulaal. But, as is argued in the present paper, more recent data show that, in some cases, presentday suffi xes may result from the association of a former suffix with an element similar to one of the Kulaal determiners. In such cases the former determiner has simply lost its independence and been historically stacked onto the noun form.