A light guide is provided. The light guide includes a planar body with a first light receiving surface, a light transmission region in optical communication with the first light receiving surface, and an aperture having an inner circumferential wall defining a light emission region, the inner circumferential wall having a plurality of vertically extending flutes. Substantially all light received at the light receiving surface internally reflects through the transmission region before extraction at the emission region. A luminaire is also provided. The luminaire includes a housing, a light guide as described herein, and a plurality of point light sources in optical communication with the light receiving surface of the light guide.