diff --git a/.travis.yml b/.travis.yml
index 7e1201e6..ed6be1dc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@ env:
   - TOXENV=py27
   - TOXENV=py33
   - TOXENV=py34
+  - TOXENV=pypy
 install: 
   - pip install -r requirements-dev.txt
   - pip install -U tox codecov
diff --git a/jose/jwk.py b/jose/jwk.py
index 839b43b8..75814de6 100644
--- a/jose/jwk.py
+++ b/jose/jwk.py
@@ -2,7 +2,6 @@
 import hashlib
 import hmac
 import six
-import struct
 
 import Crypto.Hash.SHA256
 import Crypto.Hash.SHA384
@@ -18,6 +17,13 @@
 from jose.exceptions import JWSError
 from jose.exceptions import JOSEError
 
+# PyCryptodome's RSA module doesn't have PyCrypto's _RSAobj class
+# Instead it has a class named RsaKey, which serves the same purpose.
+if hasattr(RSA, '_RSAobj'):
+    _RSAKey = RSA._RSAobj
+else:
+    _RSAKey = RSA.RsaKey
+
 
 def get_algorithm_object(algorithm):
     """
@@ -204,7 +210,7 @@ def __init__(self, hash_alg):
 
     def process_prepare_key(self, key):
 
-        if isinstance(key, (RSA._RSAobj, RSAKey)):
+        if isinstance(key, (_RSAKey, RSAKey)):
             return key
 
         if isinstance(key, dict):
diff --git a/setup.py b/setup.py
index 1f1b4cda..83643b94 100644
--- a/setup.py
+++ b/setup.py
@@ -4,6 +4,8 @@
 
 import jose
 
+import platform
+
 from setuptools import setup
 
 
@@ -22,6 +24,18 @@ def get_packages(package):
     ]
 
 
+def get_install_requires():
+    if platform.python_implementation() == 'PyPy':
+        crypto_lib = 'pycryptodome >=3.3.1, <3.4.0'
+    else:
+        crypto_lib = 'pycrypto >=2.6.0, <2.7.0'
+    return [
+        crypto_lib,
+        'six >=1.9.0, <1.10.0',
+        'ecdsa <1.0',
+    ]
+
+
 setup(
     name='python-jose',
     version=jose.__version__,
@@ -43,11 +57,8 @@ def get_packages(package):
         'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3.3',
         'Programming Language :: Python :: 3.4',
+        'Programming Language :: Python :: Implementation :: PyPy',
         'Topic :: Utilities',
     ],
-    install_requires=[
-        'pycrypto >=2.6.0, <2.7.0',
-        'six >=1.9.0, <1.10.0',
-        'ecdsa <1.0',
-    ]
+    install_requires=get_install_requires()
 )
diff --git a/tox.ini b/tox.ini
index ec2df7ba..51c1f204 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py{26,27,33,34}
+envlist = py{26,27,33,34,py}
 
 [testenv]
 commands =