A wedge diffuser, comprising: a diffuser flowbody (32, 34, 36) having an inner peripheral portion and an outer peripheral portion; diffuser flow channels extending through the diffuser flowbody, the diffuser flow channels comprising: flow channel inlets formed in the inner peripheral portion of the diffuser flowbody; flow channel outlets formed in the outer peripheral portion of the diffuser flowbody; and flow channel throats fluidly coupled between the flow channel inlets and the flow channel outlets; and diffuser vanes contained in the diffuser flowbody and partitioning the diffuser flow channels, the diffuser vanes comprising a first plurality of vane sidewalls transitioning from upstream linear sidewall geometries in a spanwise direction to downstream non-linear sidewall geometries in the spanwise direction at locations between the flow channel inlets and the flow channel outlets, wherein the first plurality of vane sidewalls transitions from linear sidewall geometries to non-linear sidewall geometries at locations of the flow channel throats, characterised in that a flow channel throat of each diffuser flow channel extends between facing diffuser vane surfaces defining a particular diffuser flow channel between a leading end of one of the diffuser vane surfaces and an intersection point of the other of the diffuser vane surfaces at which the other of the diffuser vane surfaces transitions from a linear sidewall geometry to a non-linear sidewall geometry. a diffuser flowbody (32, 34, 36) having an inner peripheral portion and an outer peripheral portion; diffuser flow channels extending through the diffuser flowbody, the diffuser flow channels comprising: flow channel inlets formed in the inner peripheral portion of the diffuser flowbody; flow channel outlets formed in the outer peripheral portion of the diffuser flowbody; and flow channel throats fluidly coupled between the flow channel inlets and the flow channel outlets; and flow channel inlets formed in the inner peripheral portion of the diffuser flowbody; flow channel outlets formed in the outer peripheral portion of the diffuser flowbody; and flow channel throats fluidly coupled between the flow channel inlets and the flow channel outlets; and diffuser vanes contained in the diffuser flowbody and partitioning the diffuser flow channels, the diffuser vanes comprising a first plurality of vane sidewalls transitioning from upstream linear sidewall geometries in a spanwise direction to downstream non-linear sidewall geometries in the spanwise direction at locations between the flow channel inlets and the flow channel outlets, wherein the first plurality of vane sidewalls transitions from linear sidewall geometries to non-linear sidewall geometries at locations of the flow channel throats, characterised in that a flow channel throat of each diffuser flow channel extends between facing diffuser vane surfaces defining a particular diffuser flow channel between a leading end of one of the diffuser vane surfaces and an intersection point of the other of the diffuser vane surfaces at which the other of the diffuser vane surfaces transitions from a linear sidewall geometry to a non-linear sidewall geometry.