The invention relates to an optical device and to a headlighting assembly including an optical device. An optical device includes a body 16 of a transparent material arranged to receive light at at least one light input portion 24a, 24b. At least a portion of the light is reflected at an outer surface 28a, 28b of the body 16 due to total internal reflection. A non-transparent housing 12 is provided to at least partially cover the body 16. The body 16 is held within the housing 12 by protrusions 30, 36 arranged to abut against the outer surface 28a, 28b.