The article presents a rule-based machine translation system from Northern Sami to Norwegian. The grammatical analysis is done with Giellatekno and Divvun's North Sami program for analysis and translation. We have written the transfer component (transfer lexicon and grammatical rules) within the framework of the open machine translation system Apertium. The article contains an evaluation of translated text for two different domains. The translated texts score better on the presentation of the content than on fluent language. By classifying the errors into lexical, grammatical and pragmatic errors, we show that lexical errors are the most harmful for text comprehension. The other two types of errors give a poor language quality, but they have little effect on comprehension. The type of error that is the easiest to correct is the lexical, which is a promising conclusion for the development of a machine translation system for text comprehension.