Linguistic diversity emerging from international student mobility, in non-anglophone universities, is typically eclipsed by the existing tensions between the national language(s) and English as 'Lingua franca'. Through a series of semi-structured interviews with university lecturers, this study highlights the tensions surrounding national languages and English and the attention paid to international student languages as resources for learning. Furthermore, using enunciation theory it seeks to show what shapes lecturers' attitudes to language use at university. It concludes that while there is some evidence that international student languages are recognised in teaching practices, there are also real concerns over maintaining the national language(s). This obscures the role that international student languages could play in teaching and learning.