Arrangement of a trim element on its support inside of a vehicle

The arrangement has a flexible fixation lug (18) with an opening cooperating with a fastening unit of a flexible fixation lug (14) of a support (12). A rigid tab (32) is arranged below the lug (18) and extends in a plane parallel to that of the lug (18) such that the lug (14) is inserted between the lug (18) and the rigid tab, when a covering unit (10) is in a fixed position.