A mounting system (1) for mounting a light fixture comprises two substantially L-shape designed receiving rails (4a, 4b). The receiving rails (4a, 4b) each have a first leg (5a, 5b) which is designed to be fastened to a front side of a suspended wall or an underside of a suspended ceiling (2) on a respective opposite edge of a recess (3) of the wall or ceiling (2). The receiving rails (4a, 4b) each further comprise a second leg (6a, 6b) which is designed to protrude into the recess (3) and to carry a light fixture housing (10) of the light fixture, but without connecting the light housing (1) rigidly to the first legs (5a, 5b) of the receiving rails (4a, 4b).