This chapter investigates the role that varieties play in the education of future teachers of English at German universities. The pluricentric and international nature of English affords many examples where varieties differ substantially at a level below the awareness even of experienced practitioners. I report major results from a questionnaire study carried out among native-speaking lectors of English teaching at German universities. Competing prepositional variants were subjected to acceptability judgements by 76 participants. The quasi-experimental pre-test/post-test design seeks, firstly, to examine their tolerance of variant forms, and secondly, to foster the view that corpora can be leveraged to handle variability. The results demonstrate that native speakers are indeed inherently limited by the habits formed by their native varieties. However, direct exposure to displays of corpus data testifying to the existence of diverging standards turns out to be inadequate to increase participants’ acceptance of the variants they are less familiar with. To overcome these limitations, the discussion suggests that a new mindset, embracing English as an International Language, will only succeed with the support of a new skillset: corpus literacy, and specifically the use of international corpora as referencing tools.