1. A method of correcting digitized map data stored in a map database of a navigation device, the map data comprising routing data in the form of route links and shape points, wherein each route link is associated with a sequence of shape points representing a course of a road segment for display on a screen, the method comprising the steps of: detecting a first user input operation indicative of a selection of a road segment displayed on the screen; detecting at least one second user input operation indicative of a graphical manipulation of the course of the selected road segment on the screen; generating on basis of the detected second user input operation corrected routing data reflecting the manipulated course of the selected road segment; and storing the corrected routing data in the map database.