A plate heat exchanger, comprising: a plurality of heat exchanger plates which are stacked and permanently connected to form a plate package that defines first and second fluid paths for a first medium and a second medium, respectively, separated by said heat exchanger plates, said plate package defining a surrounding external wall that extends in an axial direction between first and second axial ends, an end plate (21; 24) permanently connected to one of the first and second axial ends so as to provide an end surface that extends between first and second longitudinal ends in a lateral plane which is orthogonal to the axial direction, and two mounting plates permanently connected to a respective surface portion of the end surface at the first longitudinal end and the second longitudinal end, respectively, such that the mounting plates are spaced from each other in a longitudinal direction on the end surface, wherein each of the mounting plates comprises opposing flat engagement surfaces (12, 13) connected by an edge portion that extends along the perimeter of the mounting plate, wherein each of the mounting plates is arranged with one of its engagement surfaces (12, 13) permanently connected to the end surface, characterized in that the perimeter of each of the mounting plates partially extends beyond the outer periphery of the end surface, so as to define a mounting flange, and partially extends across the end surface in contact with the same, and at least one slot is formed in the edge portion of each of the mounting plates and is arranged to extend below the end surface so as to intersect the perimeter of the surrounding external wall as seen in a normal direction to the end surface. a plurality of heat exchanger plates which are stacked and permanently connected to form a plate package that defines first and second fluid paths for a first medium and a second medium, respectively, separated by said heat exchanger plates, said plate package defining a surrounding external wall that extends in an axial direction between first and second axial ends, an end plate (21; 24) permanently connected to one of the first and second axial ends so as to provide an end surface that extends between first and second longitudinal ends in a lateral plane which is orthogonal to the axial direction, and two mounting plates permanently connected to a respective surface portion of the end surface at the first longitudinal end and the second longitudinal end, respectively, such that the mounting plates are spaced from each other in a longitudinal direction on the end surface, wherein each of the mounting plates comprises opposing flat engagement surfaces (12, 13) connected by an edge portion that extends along the perimeter of the mounting plate, wherein each of the mounting plates is arranged with one of its engagement surfaces (12, 13) permanently connected to the end surface, characterized in that the perimeter of each of the mounting plates partially extends beyond the outer periphery of the end surface, so as to define a mounting flange, and partially extends across the end surface in contact with the same, and at least one slot is formed in the edge portion of each of the mounting plates and is arranged to extend below the end surface so as to intersect the perimeter of the surrounding external wall as seen in a normal direction to the end surface.