We have released and evaluated the first South Sámi grammar checker GramDivvun. It corrects two frequent error types that are caused by and causing language change and a loss of the language’s morphological richness. These general error types comprise a number of errors regarding the adjective paradigm (confusion of attributive and predicative forms) and the negation paradigm. In addition, our work includes a classification of common error types regarding the adjective and negation paradigms and lead to extensive grammatical error mark-up of our gold corpus. We achieve precisions above 71% for both adjective and negation error correction.