Disclosed is a cabin air compressor (CAC) of an aircraft environmental control system, the CAC having: a CAC case defining a forward end, an aft end axially spaced apart from the forward end, wherein the forward end defines a compressor inlet; and a supplemental cooling jacket, positioned around at least a portion of the CAC case and at least partially conforming the CAC case, and wherein the supplemental cooling jacket is configured to direct a cooling medium through it.