A fastener ring for fastening a dispenser member, such as a pump or a valve, on a neck of a reservoir, the ring including a reception mechanism suitable for receiving the dispenser member, and a substantially-cylindrical attachment skirt for coming into engagement around the neck of the reservoir. The skirt defining an inner wall that defines a top first inner wall section for coming into engagement with the neck, and a bottom second inner wall section for extending out of contact with the neck. The attachment skirt includes an orientation tab that interrupts the bottom second inner wall section and that projects radially inwards relative to the second section.