Abstract: The present invention relates to an electric motor comprising an attached additional element, in particular an incremental shaft encoder, and a mounting base plate which has seated thereon the additional element and is connected to the electric motor such that its angular position is adjustable during assembly. The adjustability of the angular position is to be improved, whereby mounting is simplified. To this end, a profile toothing is provided on the electric motor and a counter-profile toothing on the mounting base plate, the toothings engaging each other in a substantially accurately fitting manner, thereby permitting a mounting of the base plate in different angular positions in angular steps which are predetermined by the tooth pitch.