A peristaltic pump is provided comprising a drive unit, a pumphead comprising a pressing element. The pumphead is connectable to the drive unit such that, when connected, the pressing element is driveable by the drive unit to exert a peristaltic action on a tube arranged within the pumphead. The pumphead further comprises an optical sensor, wherein the optical sensor comprises an emitter and a receiver which are mounted on the drive unit and a reflector element mounted on the pumphead. The reflector element is arranged on the pumphead such that when the pumphead is connected to the drive unit, radiation emitted by the emitter is reflected by the reflector element towards the receiver.