This paper presents FipsOrtho, a spell checker targeted at learners of French, and a corpus of learners' errors which has been gathered to test the system and to get a sample of specific language learners' errors. Spell checkers are a standard feature of many software products, however they are not designed for specific language learners' errors. After a brief review of the state of the art, we describe the system's architecture and interfaces. Then we describe our error typology and detail the techniques used to retrieve words and to order proposals appropriately: alphacode, phoneticization, ad-hoc, capitalization, apostrophe, and word separation error methods. Proposals are sorted by a score depending on the method(s) used to retrieve them, on the expected lexical category, gender, number and person, and on the string proximity with the unknown word. Then the test results are presented: a list of individual words containing errors was submitted to the alphacode and phoneticization methods; a corpus of authentic learners' errors was gathered and analyzed. Finally we conclude the paper with some limitations of the system and ideas for future research.