This article revisits the provenance of the preverbal imperfective aspect marker ka, which characterizes the French-lexicon creoles of the Lesser Antilles and French Guiana and sets them apart from those of Haiti, Louisiana, and the Indian Ocean, which instead employ reflexes of après ‘after’. The origin of ka is controversial and still not properly understood. We argue that earlier proposals have focused too narrowly on the syntactic properties of the alleged source constructions, while neglecting semantic and functional motivations. We show that the emergence of ka follows the well-attested Location Schema, i.e. the grammaticalization pathway from locative predication to progressive aspect, and identify the French locative construction n’(en) être qu’à X ‘to be only at X’ as the most plausible source. In addition to its semantic aptness, the perceptual salience of this construction made it an ideal candidate for grammaticalization in a creolizing context. We bolster our argumentation by means of typological data from creoles and non-creoles. By situating ka within this broader typological framework, the article not only solves a much-debated etymological puzzle, but also demonstrates that, although creoles innovate, the cognitive-semantic mechanisms shaping their grammars are essentially the same as those shaping ‘traditional’ languages.