Abstract: A fastening device (14) consisting of a plate bent to form what is essentially a U profile. The shanks (32) of this plate each comprise a narrow section (34), the end of which widens to form a pair of hooks (36, 38). The hooks are provided in order to allow attachment of the device to a vertical supporting rail (12) through the introduction of the shanks into corresponding parallel slots (20) in the rail, by which means a corresponding mounting device (26) on a screen or wall panel (10) can be hooked in between the rail (12) and the rib (30) of the fastening device itself. In order to prevent the fastening device from coming loose and falling out when a screen or wall panel is removed, at least one hook (36) of each shank (32) is provided with a projection (40) directed towards the rib of the fastening device.