A lighting fixture is provided that includes a flat elongated base having opposing longitudinal marginal slots and a pair of upright walls inboard of the longitudinal slots, and a pair of end caps engaging opposing ends of the elongated base. A gasket extends along a longitudinal surface of each of the upright walls. A lens extends between opposing end caps and conforms to the curved marginal edges of the end caps and edges and upright walls. The lens has two opposing longitudinal grooves that align with a pair of side rails extending between the end caps. Each side rail has a longitudinal cam projection extending into the associated lens groove. When the side rails are tightened against the lens, the cam projections tighten the lens into contact with the gasket to form a water tight seal between the lens and the base.