Pip install cryptography in windows

I'm get the following error when running pip install cryptography:

build\temp.win32-2.7\Release\_openssl.c(434) : fatal error C1083: Cannot open include file: 'openssl/opensslv.h': No such file or directory

I'm running windows 10, 64 bit, with python 2.7. I'm trying to install cryptography 1.9.