Greenberg (1978) proposes a diachronic scenario of change through morphologization and generalisation from demonstratives (Stage 0) to gender markers (Stage III), with definite articles (Stage I) and non-generic articles (Stage II) as intermediary steps. Although there is ample evidence for the cyclical application of this scenario in the Niger-Congo languages, there are very few Niger-Congo languages that can be analysed as having definite articles. We argue that this is because definiteness distinctions are not part of the grammar of Niger-Congo languages. That is, nominal expressions are not obligatorily either definite or indefinite in Niger-Congo. We discuss linguistic elements that have been analysed as definite articles in Bantu and Mande languages, because they can be used to signal familiarity or uniqueness, and show that their use is both optional and restricted in ways that are not expected of the markers of grammatical feature values.