I think I read somewhere that if you modify the source of a software enough, you become the owner ("author") of that source.

First I'd like to make sure that this is correct. If not, then the point is moot.

If it is possible, then I'm wondering how many such changes are required to indeed switch the ownership of the new work to a new author.

In my case, the main code is pretty much the same, however, it now includes many more error checks. My problem is that this very small small part of the code which is licensed under the GPLv2 and used in a library which I would like to make LGPLv2 compatible.

If that helps, the original code is pretty old (1990-1997 and a few more changes in 1999), but I guess that copyrights hold for 70 years, at least in the Western World...

The current code in question is on github (there is also a .h) The older version in the zipios project is available on Sourceforge.net in a CVS repository (the tarball under Files is already an updated version.)

  • 3
    I don't think "editor" is a formal term in either FLOSS licensing or general copyright law. I'm pretty sure you're the author of your derivative work the moment you create it. What is leading to this question? Where does being the formal author matter to you? Either way, you can't turn a GPL work into a LGPL work without the original author's permission. Apr 2, 2019 at 3:53
  • So that's just it... I have to rewrite that small part from scratch if I want to use it in an LGPL library. Apr 2, 2019 at 4:26
  • Do you mean the original code is very small, or your changes are very small? Apr 2, 2019 at 4:28
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    Oh I see now, it's only dostime.c/.h which is GPL, the rest is LGPL. Yes in that case re-implementing that file (or finding a LGPL compatible alternative) is the way to go. Apr 2, 2019 at 4:30
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    "if you modify the source of a software enough, you become the owner ('author') of that source." - No, this is not correct. But please see Theseus' Paradox applied to code copyright. See also "clean room", "derivative work", "original work", "reimplementation" etc.
    – Brandin
    Apr 2, 2019 at 7:13

1 Answer 1


I think I read somewhere that if you modify the source of a software enough, you become the owner ("author") of that source.

First I'd like to make sure that this is correct.

It isn't. If you make enough changes to a copyrighted work to yourself qualify for copyright protection, then both you and the original rightsholder now have a copyright interest in the resulting work. Any decisions about sale, relicensing, etc., over and above the original author's licence grant will need the consent of all rightsholders.

So: you have written a library which you wish to release under LGPLv2, but which incorporates some third-party GPLv2 code. You correctly note that this is not possible without violating the third party's licence terms.

The problem with simply re-writing the GPLv2 code is that you've read it; re-writing it at this stage opens you up to accusations of copyright infringement, since it is possible that you'll be creating a derivative work of the original code, which GPLv2 requires also to be licensed under GPLv2. As Brandin notes above, the normal path around this is the clean-room reimplementation, which you can't do on your own.

As curiousdanii notes, finding a drop-in replacement released under a non-copyleft free licence would be another solution to your problem.

That said, even if the original authors were to resurface, it is possible they would not go to the trouble of hauling you over the coals. You're not planning on making money from your code, you've made some good-faith efforts to contact the original developers to ask for permission, and it sounds as if their code forms a small part of your larger work; it is possible that in practice you'd be OK. Nevertheless, IANAL/IANYL, so you should take proper legal advice before exposing yourself to that risk.

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