The invention provides a clamping system (1) for a rotary tool (70), for example a milling cutter or drill. The clamping system (1) includes a base element (10), a collet (30) and a clamping nut (50), said clamping nut (50) friction-locking the rotary tool (70) within the base element (10) with the collet (30). In order to avoid a relative rotation of the base element (10) and the collet (30), the clamping system (1) has a form locking anti-twist protection which blocks a rotation of the collet (30) relative to the base element (10).