In the note, the author focuses on the additional drawing made by an unknown reader on the miniature of the Old Rus' illuminated manuscript of the Tale of the Route of Mamai. The drawing depicts the image of the Mandylion over one of the key scenes of the Tale: Dmitry Donskoy receiving the blessing and prosphoron from St Sergius of Radonezh. The author examines both, the text, that is illustrated, which cites the monastic rite of Panagia, and the symbolism of the image of the Holy Saviour Not Made by Hands, to conclude whether the addition was accidental or not.