I worked around the problem by uninstalling the gmp library.
I’m on OS X so I did:
brew uninstall gmp
(If you’re on a different platform, replace “brew” with your package manager —
Then things worked:
(pypy-pycrypto)marca@marca-mac:~/python/virtualenvs$ pip install PyCrypto Downloading/unpacking PyCrypto Real name of requirement PyCrypto is pycrypto Using download cache from /Users/marca/.pip/download-cache/https%3A%2F%2Fpypi.python.org%2Fpackages%2Fsource%2Fp%2Fpycrypto%2Fpycrypto-2.6.1.tar.gz Running setup.py egg_info for package PyCrypto Installing collected packages: PyCrypto ... Successfully installed PyCrypto Cleaning up...