This study explores the potential of the English File Pronunciation (EFP) app to help foreign language learners improve their pronunciation. Participants were 52 Spanish EFL learners enrolled in an English Studies degree. Pre- and post-tests were used to assess the participants' perception and production (imitative, controlled, and spontaneous) before and after training. The targets addressed were a range of segmental features that tend to be fossilised in the interlanguage of advanced Spanish EFL learners, namely English /[ash] [open back unrounded vowel]? [open-mid back unrounded vowel] [schwa]/ and the /s - z/ contrast. Training took place over a period of two weeks in which participants used the English File pronunciation app for around 20 minutes a day. Participants were randomly assigned to two groups (control and experimental). However, after the post-test, the group that had acted as control started to receive instruction and, after two weeks, took a second post-test, therefore acting as experimental too. Training fostered substantial improvements in the learners' perception and production of the target features, although the differences between groups were not statistically significant for every sound or in every task.