A ditch molding has a head with left and right wings that lap onto the roof, a stem depending from the head, and an enlarged foot at the lower end of the stem. A molding clip has a base mounted in the ditch and left and right biasing arms have wedge faces that engage with the foot to urge the foot downwardly into the ditch, establishing an installed position of the molding. The left and right biasing arms yield away from each other upon an upward movement of the foot. Left and right trap arms also provided on the clip have trap ends overlying the foot of the molding in spaced relation there from when the molding is in the installed position. Upward movement of the foot causes the foot to engage with the trap ends of the trap arms, trapping the foot against further upward movement.