The paper explores the phonological awareness of L1 among advanced adult speakers of EFL in the context of L2 pronunciation training. The subjects are students of English with Polish, Spanish, Turkish and Russian L1 background. All subjects have participated in intensive English pronunciation instruction as part of their degree training, in the English Department at the Pedagogical University in Kraków. Two aspects are tar- geted for examination: perception of sound contrasts and awareness of contextual variants in L1, mostly those pertaining to the consonantal and vocalic inventories, all related to their L2 (English) production goals. The material is based on longitudinal examination of course test results over the span of 3 years. The analysis reveals low sound discrimination skills in the subjects’ L1, largely based on letter-to-sound correspondences and inability to see beyond print. Through explicit training in their L2 they become more sensitive to the inventory and the details of their L1 sound system, the awareness they can use to the advantage when targeting L2 sound production.