Compiled computer code comprising computer code instructions organized in a plurality of basic blocks is obfuscated by replacing a jump instruction in a first basic block with a function call with at least one parameter, wherein the function call when executed determines the address of the next function to execute in dependence on the parameter; inserting into the compiled computer code an instruction that allocates a value to the parameter, the value being such that the address determined by the function call corresponds to the address of the replace jump instruction. The allocation function is inserted into the computer code in a second basic block, different from the first basic block, preferably using information from a control flow graph. This can ensure that the obfuscated code cannot be disassembled without information from the CFG, while the CFG cannot be generated from the obfuscated code. Also provided is a device for code obfuscation.