A washer is configured to be secured underneath a flange of a fastening clip assembly. The washer includes an annular support ring defining a central channel and having a first surface and a second surface that is opposite from the first surface. The first surface is configured to abut into and sealingly engage the flange at two or more locations. An inner sealing rim extends from the second surface proximate to the central channel. The inner sealing rim is configured to sealingly engage a component at a first component sealing interface. An outer sealing rim extends from the second surface and is outwardly separated from the inner sealing rim by a gap. The outer sealing rim is configured to sealingly engage the component at a second component sealing interface.