Korandje, a Songhay language spoken in Tabelbala (Algeria), has been extensively influenced by Berber, borrowing more than 50 verbs. In the process, Korandje (predominantly agglutinative) is forced to select a single invariant stem from the many forms of the Berber verb, whose several principal parts are often interrelated by stem-internal changes as well as affixation. It turns out that the form chosen is almost always the perfective, with or without a 3MSG prefix depending on the conjugation.  This matches well with the structure of Korandje, where the absence of an overt mood/aspect marker marks the perfective, and with results observed in related languages. As such, it suggests that recipient language structure helps determine the outcome of language contact.