diff --git a/setup.py b/setup.py
index d06b861..34e06d7 100644
--- a/setup.py
+++ b/setup.py
@@ -34,8 +34,14 @@ setup(name="magic-wormhole",
           "hkdf", "tqdm",
           "click",
       ],
-      extras_require={':sys_platform=="win32"': ["pypiwin32"],
-                      "tor": ["txtorcon", "ipaddress"]},
+      extras_require={
+          ':sys_platform=="win32"': ["pypiwin32"],
+          "tor": ["txtorcon", "ipaddress"],
+          "dev": [
+              "mock",
+              "tox",
+          ],
+      },
       test_suite="wormhole.test",
       cmdclass=commands,
       )
diff --git a/tox.ini b/tox.ini
index 36a1650..cea30da 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = {py27,py33,py34,py35}
+envlist = {py27,py33,py34,py35,pypy}
 skip_missing_interpreters = True
 
 # On windows we need "pypiwin32" installed. It's supposedly possible to make