Just in case the author shows up here, there's a confusing little typo in "Passing argv to our program": _start: popq %rdi movq %rsp, %rdi c

Just in case the author shows up here, there's a confusing little typo in "Passing argv to our program": _start: popq %rdi movq %rsp, %rdi callq main the second %rdi should be %rsi, which is confirmed by the explanatory test: > If it's really that easy all we will need to do is add movq %rsp, %rsi after the popq %rdi we just added. EDIT: now fixed