A compressor (10) has a rotor assembly (12) having an impeller (42) for generating an airflow through the compressor (10), a stator core assembly (16, 18,20,22) for causing rotation of the impeller (42), and a diffuser assembly (28) for acting on the airflow generated by the impeller (42). The diffuser assembly (28) has a first diffuser stage (100) and a second diffuser stage (200). The first (100) and second (200) diffuser stages are separate components connected to one another by a fastener (108).