diff --git a/setup.py b/setup.py
index f12714d..3d3fe04 100755
--- a/setup.py
+++ b/setup.py
@@ -34,7 +34,7 @@
       maintainer_email = 'exarkun@twistedmatrix.com',
       url = 'https://github.com/pyca/pyopenssl',
       license = 'APL2',
-      install_requires=["cryptography>=0.3", "six>=1.5.2"],
+      install_requires=["cryptography>=0.4", "six>=1.5.2"],
       long_description = """\
 High-level wrapper around a subset of the OpenSSL library, includes
  * SSL.Connection objects, wrapping the methods of Python's portable