Abstract: A supplemental right turn signal is provided for a semitrailer having the forward end thereof pivotally attached to the rear of a tractor. The supplemental right turn signal is held on the face of a vertically disposed support member which is mounted beneath the bed of the chassis of the semitrailer adjacent the right landing gear provided therefor. The support member is held by attaching the top thereof to one of the transverse structural beams supporting the bed of the semitrailer and by attaching the bottom thereof to the lower end of a bracket, the upper end of which is attached to the next forward transverse structural beam.