Did you know it is possible to change the behavior of a compiled program by editing the machine code directly rather than recompiling it from source? Though well-known by hackers, firmware engineers, and other low-level types, this can be intriguing to those whose main focus is in other areas of computer science. By focusing on removing a restriction added to Mozilla Firefox between version 52 ESR and 60 ESR, I show from the ground up how to edit a binary to bypass a plugin check, with mixed results. I use only basic GNU binutils tools to focus on the “bits and bytes” and not on how to use a particular tool. If you are interested in brushing up on some x86–64 assembly, basic reverse engineering and hex editing, take a look at this blog.