1. A computing device comprising means to store and execute bytecodes, the computing device storing bytecodes having a bytecode for calling a method and wherein the bytecode calling a sensitive method is followed by an attack detection bytecode present after the bytecode for calling the method, and in that when executing bytecode, the computing device, upon return from the method, operates to continue bytecode execution after the attack detection bytecode, and wherein execution of the attack detection bytecode upon return from the method is indicative of an error in execution of the method thereby protecting against fault attacks during the execution of the bytecode for calling the method.