This paper addresses the relevance of pragmatic competence in foreign language learning and analyses how pragmatic errors or deficiencies, far from being simple communicative failures, can become a valuable teaching resource. Based on the notion of pragmatic competence and its associated errors, pragmatic deficiencies, it is argued that these deficiencies function as a ’watermark’ that reveals the non–native speaker. Far from conceiving them solely as obstacles, the proposal is to take advantage of errors as a driver of learning through activities that develop the student’s pragmatic awareness. Within this framework, pragmatemes —phraseological units fixed in specific contexts of use— are presented as ideal material for teaching. A teaching sequence is presented based on the identification of errors in pragmatemes from different languages, comparison with machine translations, and verification through authentic sources