An in-line heater for a liquid food or beverage preparation machine, in which machine liquid is circulated through the heater and then guided into a brewing chamber for brewing a food or beverage ingredient supplied into said brewing chamber. The heater has a body incorporating an inlet, an outlet and a heating chamber extending therebetween, with the inlet, outlet and heating chamber forming together a rigid passage for guiding the liquid circulating through the body, and one or more electric components that are secured on or in the body and connected to a printed circuit board arranged to control the heater. The one or more electric components are rigidly connected to the printed circuit board.