We present GramDivvun, the first Inari Saami grammar checker for L2 users. The grammar checker is an important tool in the revitalisation of the language, in particular for strengthening the literary language. As the Inari Saami language community needs language tools predominantly for language learners, the focus is on grammatical interference errors made by (mostly Finnish-speaking) learners. Six of these errors are featured in the first version of the grammar checker. For non-proofread text written by inexperienced writers, precision is good, 73%. With experienced text and proofread text, alarms are rare but precision considerably lower, 19.5 % on average, but varying considerably between the error types. The paper discusses reasons for this variation. Future plans are improving results by means of increased testing, especially for complex sentences, and eventually also including more error types.