A knotter for a baler, the knotter including a knotting system with at least one movable part, and a driver, operatively connected to the at least one movable part. The knotter is further provided with a first cover, associated with at least one movable part, having a first covering position wherein the first cover at least partly covers the at least one movable part, and a second uncovering position, wherein the first cover no longer covers the at least one movable part. The knotter further includes a safety mechanism, operatively connected to the driver and the first cover, such that positioning or enabling the positioning of the first cover in the second uncovering position stops the moving of the at least one movable part.