A guard for a rotatable wheel of a power tool is disclosed. The guard comprises a shroud which is configured to partially enclose the wheel and a port disposed at a circumferential position on the shroud, via which debris generated by the wheel during use can exit the shroud. The shroud comprises a radii of curvature which increases between a first angular position and a second angular position, relative to a rotational axis of the wheel, in a direction comprising a rotational direction of the wheel.