A mounting device (110) for reversibly mounting at least one electromagnetic field generator (112) on an ultrasonic probe (114) for orientating the electromagnetic field generator (112) with respect to the ultrasonic probe (114) in at least one mounting position (116) is disclosed. The mounting device (110) comprises at least one first fastening structure (118). The mounting device (110) is connectable to the electromagnetic field generator (112) via the first fastening structure (118).