A twin tube locking assembly for a hand-held spray gun using an extended suction set of a hose and fitting the assembly including a ring having a body with a cylindrical skirt portion and a planar wall retaining a flange of the fitting of the suction set to a pump housing of the gun. The ring is positionable to a first position permitting engagement and disengagement of the ring to the pump housing and a second position retaining the extended suction set to the pump housing by the interaction of a margin of a fan shaped aperture in the planar wall of the ring urging a flange of a fitting of the extended suction set towards the pump housing when a plurality of lips on the housing engage and retain respective lugs on the ring. A detent member on the ring is movable past a stop member on the housing to secure the ring in the engaged position. The planar wall is deformed when the ring is engaged with the housing to secure the fitting against the housing.