English loanwords with /ʌ/ that are part of the Brazilian Portuguese (BP) lexicon are normally produced with [ɐ] (pub: [ˈpɐbɪ]). Although [ɐ] is the closest segment to /ʌ/ in the native inventory, it is highly constrained in BP: it is an allophone of /a/ that can only appear in nasal contexts. This paper investigates whether native speakers of BP generalize to novel loanwords the adaptation pattern of English /ʌ/ that is present in the BP lexicon. Two experiments were conducted, one with real loanwords and one with nonce loanwords. In the Real Loanword Experiment, participants consistently used [ɐ] both in oral (pub) and nasal contexts (funk), as predicted given the patterns in the lexicon. In the Nonce Loanword Experiment, participants used [ɐ] significantly more frequently in nasal contexts – in oral contexts, the most frequent adaptation was [a]. This reveals that speakers employ their native grammar to filter new loanwords: in contexts where [ɐ] is not licensed, they favor the corresponding licensed form. These results suggest that native speakers do not generalize non-native patterns that are present in the lexicon, mirroring what has been observed for the generalization of unnatural patterns in native grammars (e.g., Garcia 2017; Jarosz 2017).