A hook fastener having a closure for closing a hook mouth. A keeper selectively prevents opening of the closure and includes a body having a base and a hook extending from the base to define a gap. The base has an external face and an opening with a mouth intersecting the external face. The closure includes a shaft and a grip, the grip protruding from the shaft through the mouth. A spring urges the closure such that the shaft may selectively extend out of the opening. The keeper is received to rotate upon the external face. A slot in the keeper extends parallel to the mouth, the keeper selectively preventing the user from retracting the closure from the gap.