diff --git a/setup.py b/setup.py
index 19d0f094..8811ae2e 100755
--- a/setup.py
+++ b/setup.py
@@ -72,7 +72,7 @@
 from setuptools import find_packages
 
 extras = {
-  'tools': ['pycrypto>=2.6.1', 'pynacl>=0.2.3']
+  'tools': ['cryptography>=1.4.0', 'pycrypto>=2.6.1', 'pynacl>=0.2.3']
 }
 
 with open('README.rst') as file_object: