This combined ERP and behavioral experiment explores the dynamics of processing during the discrimination of vowels in a non-native regional variety. Southern listeners were presented with three word forms, two of which are encountered in both Standard and Southern French ([kɔt] and [kut]), whereas the third one exists in Standard but not Southern French ([kot]). EEG recordings suggest that all of the word pairs were discriminated by the listeners, although discrimination arose about 100 ms later for the pairs which included the non-native word form than for those which contained word forms common to both French varieties. Behavioral data provide evidence that vowel discrimination is sensitive to the influence of the listeners' native phonemic inventory at a late decisional stage of processing.