A recent GAS update changed the length of this instruction: adc 0(%ebx,%ecx,4),%edx Previously, it was encoded as a four-octet sequence, now it's equivalent to: adc (%ebx,%ecx,4),%edx -- which only needs three octets. Is there a way to force the old behavior, without inserting nops? (If not, I will hard-code the opcodes.)