Abstract: A light-emitting device for a motor vehicle headlamp, said device comprising a housing, a light source disposed on said housing and an optical device directing one or more light beams emitted by said source, said housing comprising a projecting element for allowing a fixed position of said optical element with respect to said housing. This device is noteworthy in that said projecting element comprises at least one hollow rib formed inside an enclosure defined by said housing and said optical device comprises, opposite the housing, a slot that nests at least partially with said hollow rib of said housing. The invention also relates to a headlamp, in particular for a motor vehicle, comprising said emitting device.