Abstract: In a fastening system of a roller bearing, comprising a bearing unit (3) which has a roll pin (1) that is mounted in a roll pin bearing (8) therein and a threaded nut (9) that engages in a thread formed on the roll pin (1) or a tensioning anchor (5) fastened therein and fixes the bearing unit (3) on the roll pin (1), a solution is to be created that improves the self-locking anti-turn mechanism of a threaded nut holding a roll pin bearing in place. According to the invention, a bendable and movable partial section (9a) is formed on the threaded nut (9), which section can be moved, particularly bent, relative to the remaining part (9b) of the threaded nut (9) into a position creating surface pressure (15b, 16b) that acts opposite the remaining thread engagement of the threaded nut (9) in the thread.