Although spell checkers are commonplace in numerous software products, errors specifically made by learners of a target language may not be sufficiently catered for. This is because generic spell checkers function on the assumption that their users are competent speakers of the target language, whose misspellings are primarily due to accidental typographical errors. The majority of misspellings were found to be attributed to systematic competence errors instead of accidental typographical ones, with up to 48% of these errors failing to be detected or corrected by the generic spell checker used.