A compressor for compressing a gas, the compressor comprising: a housing having an axial inlet and an annular outlet volute; an impeller wheel including a plurality of blades, the wheel being rotatably mounted within the housing between the inlet and outlet volute; the axial inlet being defined by a tubular inducer portion of the housing and the annular outlet volute being defined by an annular diffuser passage surrounding the impeller, the diffuser having an annular outlet communicating with the outlet volute; the housing having an inner wall defining a surface located in close proximity to radially outer edges of the impeller blades which sweep across the surface as the impeller wheel rotates; wherein the compressor housing incorporates at least one section comprised of a deformable, energy absorbing material arranged to deform and absorb energy generated as a result of impeller wheel failure. A turbine incorporating similar deformable, energy absorbing materials is also described, as are turbochargers incorporating such a compressor and/or turbine.