The present invention discloses a labelling machine and method for its operation. The labelling machine comprises a supply spool support (10) for supporting a supply spool comprising label stock comprising a web and a plurality of labels, the plurality of labels being attached to the web and being separable from the web; a take-up spool support (12) adapted to take up a portion of web; a sensor (52) configured to produce a sensor signal (56) indicative of a periodic property of at least a portion of the label stock; and a controller configured to calculate a displacement of the web along a web path defined between the supply spool and the take-up spool based upon the sensor signal and a length of a component of the label stock.