This disclosure provides a cross key anti rotation spacer for use in a gas turbine engine. A compressor disk assembly can have a cross key ring having a plurality of keys, teeth, or castellations, alternating with a plurality of gaps to form a cross key surface. The keys or teeth of the cross key surface can mesh with corresponding teeth formed on a spacer of a compressor rotor assembly. The spacer teeth, in connection with the teeth or keys of the cross key ring can prevent rotation between the spacer and compressor disk. This is particularly beneficial during transient operations, such as startup and shutdown of the gas turbine engine.