hi, numpy.random is largely built from a cython file. Up to know numpy git included generated c sources for this one file. It is troublesome to have merge 20k line changes for one line bugfixes, so it is proposed to remove the generated sources from the master branch in this PR: https://github.com/numpy/numpy/pull/4589 Like in SciPy the sources will not be contained in git anymore but built by the regular setup.py build when required. Release source tarballs (sdist) will continue contain the generated sources so users of stable release are not required to have cython installed. If you have any objects to this please speak up soon. Cheers, Julian