diff --git a/tests/test_napoleon.py b/tests/test_napoleon.py
index d8c719609..9ec36efaf 100644
--- a/tests/test_napoleon.py
+++ b/tests/test_napoleon.py
@@ -10,7 +10,11 @@
     :license: BSD, see LICENSE for details.
 """
 
-from mock import Mock
+try:
+    # Python >=3.3
+    from unittest.mock import Mock
+except ImportError:
+    from mock import Mock
 from sphinx.application import Sphinx
 from sphinx.ext.napoleon import (_process_docstring, _skip_member, Config,
                                  setup)
diff --git a/tox.ini b/tox.ini
index 6d09f305d..a9072acf6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,7 +3,6 @@ envlist=py26,py27,py32,py33,pypy,du11,du10
 
 [testenv]
 deps=
-    mock
     nose
     sqlalchemy
     whoosh
@@ -13,8 +12,24 @@ commands=
     {envpython} tests/run.py {posargs}
     sphinx-build -W -b html -d {envtmpdir}/doctrees doc {envtmpdir}/html
 
+[testenv:py26]
+deps=
+    mock
+    {[testenv]deps}
+
+[testenv:py27]
+deps=
+    mock
+    {[testenv]deps}
+
+[testenv:py32]
+deps=
+    mock
+    {[testenv]deps}
+
 [testenv:pypy]
 deps=
+    mock
     simplejson
     {[testenv]deps}