The orthography of Gikuyu includes a number of accented characters to represent the entire vowel system. These characters are however not readily available on standard computer keyboards and are usually represented as the nearest available character. This can render reading and understanding written texts more difficult. This paper describes a system that is able to automatically place these accents in Gikuyu text on the basis of local graphemic context. This approach avoids the need for an extensive digital lexicon, typically not available for resource-scarce languages. Using an extended trigram based-approach, the experiments show that this method can achieve a very high accuracy even with a limited amount of digitally available textual data. The experiments on Gikuyu are contrasted with experiments on French, German and Dutch.