A retaining system (100) for a DTH hammer drill bit (25) having an outer surface with a plurality of stops (31) at an up-hole end (29) of the drill bit (25) the stops projecting radially outward from the outer surface and spaced by respective gaps (35). The retaining system has a ring (102) which is configured to pass over the stops (31) when in a first rotational position relative to the drill bit (25). However when the ring (102) is in a second rotational position relative to the drill bit (25) it prohibits passage of the stops (31) through the ring (102).