A brazed plate heat exchanger (10) comprising a stack of heat exchanger plates (12a, 12b) provided with a pattern comprising ridges (R) and grooves (G) to form plate interspaces (13a, 13b) for fluids to exchange heat. The heat exchanger plates are provided with port openings (O1-O4) forming inlet and outlet channels (14) for the first and second fluids, wherein at least one of the first and second heat exchanger plates is arranged with a skirt to form a chamber (17) between the port opening and the plate interspaces. The chamber (17) is open to the channel (14) through a gap between at least a free end portion of the skirt and the adjacent heat exchanger plate, and the gap varies around the circumference of the channel (14) and/or a cross section area of the chamber (17) varies around the circumference of the channel (14).