diff --git a/README b/README
index bebaffd..2c21495 100644
--- a/README
+++ b/README
@@ -59,6 +59,11 @@ Alternatively, if you have testrepository installed:
     testr init
     testr run
 
+You should install all optional dependencies, e.g. by creating a virtualenv
+and using:
+
+    pip install -e '.[testing]'
+
 The included ARC tests are very limited.  The primary testing method for ARC
 is using the ARC test suite: https://github.com/ValiMail/arc_test_suite
 
diff --git a/setup.py b/setup.py
index 07a1b67..833f09b 100644
--- a/setup.py
+++ b/setup.py
@@ -77,7 +77,11 @@ verification.""",
       ],
     zip_safe = False,
     extras_require={
-        'ed25519':  ['PyNaCl'],
+        'testing': [
+            'authres',
+            'pynacl',
+        ],
+        'ed25519':  ['pynacl'],
         'ARC': ['authres']
     },
     **kw