The invention relates to a luminous motor-vehicle module including at least one light source, an open casing, and a closing element for closing said open casing. The open casing includes a housing for positioning on an optical element, the positioning housing includes a plurality of grooves, and a tab for hooking on a casing of said motor vehicle comprising the optical element and an outer lens for closing the casing, the luminous module being configured to make a rotation and hook, at the end of the rotation, onto the casing via said hooking tab of the open casing.