This article explores the use of vague expressions in English spoken as a lingua franca in academic settings. The main focus is on the frequencies of general extenders (e.g. and so on), vague classifiers (e.g. some sort of), metadiscourse particles (e.g. so to say), and indefinite prepositional phrases (e.g. in a way). The aim of the study is to investigate how non-native speakers using English as a lingua franca employ and modify their repertoire of lexical vagueness in accordance with the speech event type and academic domain. Furthermore, the study also presents comparisons between the frequencies of vague expressions in lingua franca and native speaker data. The main sample is drawn from the English as a Lingua Franca in Academic Settings (ELFA) corpus and the findings are contrasted with a comparable data from the Michigan Corpus of Academic Spoken English (MICASE). The findings show that, on the whole, lingua franca speakers employ vague expressions almost twice as frequently as native speakers, although the range of different expressions was found to be narrower in the lingua franca data. Vague expressions were most commonly found in dialogic speech events such as doctoral defense and seminar discussions. As regards academic domains, vague expressions were most often used in technology, while in humanities and social sciences their frequencies were lower.