The present paper deals with the use of two Cyrillic letters (named jus) in the 16th-century Ukrainian manuscripts kept in Hungary. The majority of the codices contains both of these special letters, however, in a number of manuscripts, the confusion of the juses can be observed. The scribes probably tried to follow Middle Bulgarian norms but the orthographic features of the protographs could also appear in the copies weakening the outcome contrary to the scribes’ intention to follow the rules.