Windage cover plates are secured between the wheels (38, 40) and spacer (39) of a turbine rotor to prevent hot flow path gas ingestion into the wheelspace cavities. Each cover plate (52) includes a linear, axially extending body (60) curved circumferentially with a radially outwardly directed wall (66) at one axial end. The wall (66) defines a axially opening recess (70) for receiving a dovetail lug. The cover plate (52) includes an axially extending tongue (63) received in a circumferential groove of the spacer. The cover plate (52) is secured with the tongue (63) in the groove and dovetail lug in the recess (70). Lap joints between circumferentially adjacent cover plates are provided.