A fluid dispenser having a piston pump mechanism and a pump driver. The pump mechanism has two piston arms, each piston arm having an inwardly extending piston tip. Each piston tip has a downwardly directed catching shoulder and an upwardly and inwardly directed camming surface. The pump driver has a first driver hook and a second driver hook, each of the driver hooks having an outwardly extending driver tip with an upwardly directed catch shoulder and a downwardly and outwardly directed cam surface. The pump driver is coupled to the pump by moving the pump driver downwards so that engagement of the cam surfaces of the driver hooks with the camming surfaces of the piston arms deflects the piston arms outwardly, until the driver tips move below the piston tips, allowing the piston arms to move inwardly to a coupled position.