diff --git a/setup.py b/setup.py
index d6e4625..7eaed7e 100755
--- a/setup.py
+++ b/setup.py
@@ -54,6 +54,7 @@ setup(
     packages=find_packages(),
     include_package_data=True,
     install_requires=[
-        'six>=1.6.1'
+        'six>=1.6.1',
+        'pycrypto==2.6.1'
     ]
 )