Hi all, Setuptools is going to re-enable a setting which makes it prefer its vendored copy of distutils over the distutils code in the stdlib in two weeks. If you only use setuptools and not numpy.distutils directly, then you're probably fine. If you do use numpy.distutils, then your build may break. It's recommended you test this now - see https://twitter.com/jaraco/status/1467660250954317827 for how. Note that it's not possible to avoid/fix this kind of breakage in a sensible fashion before it happens. Setuptools is going to be making significant backwards-incompatible changes to distutils, so if you are using numpy.distutils then you should be prepared for regular breakage. If you release your package regularly, then it's recommended you always pin setuptools in your pyproject.toml to the last version that's known to work. Setuptools typically just works and the pin will only affect your own from-source installs. The reason not to pin is if you release very irregularly - your package may then need a newer setuptools for Python 3.11 support in Oct'22 for example. It's a trade-off between avoiding breakage and not getting support for new Python versions and bug fixes. Also note the tracking issues for this build system interaction are at: https://github.com/numpy/numpy/issues/18588 https://github.com/pypa/setuptools/issues/2372 Cheers, Ralf