A mechanism for adjusting occlusion of a roller pump is described, wherein the mechanism is provided with: an elongated rod member oriented on a central axis of a pump head of the roller pump; and a drive member attached to the elongated rod member so as to move along the elongated rod member between a first position and a second position, wherein the drive member is connected to each roller block of a pump rotor of the pump head so that movement of the drive member by constant increments along the elongated rod member causes non-uniform and/or non-linear incremental movement of each roller block in a direction radial to the central axis of the pump head.