Thanks Stefan. So: nim c -r modifyframe
fails after 6 frames as explained before. arc fails for me: $ nim c --gc:arc modifyframe Hint: used config file '/home/jose/.choosenim/toolchains/nim-1.0.6/config/nim.cfg' [Conf] command line(1, 2) Error: 'none', 'boehm' or 'refc' expected, but 'arc' found With valgrind (first time using it) takes me a bit further (14 frames). I pasted the outcome [here](https://pastebin.com/YbbnmzBv). If I activate more flags I get this <https://pastebin.com/Y4AKfrku>. I don't know what to do with that information :O/.