diff --git a/doc/source/api/fixture.rst b/doc/source/api/fixture.rst
new file mode 100644
index 0000000..0f9bd8a
--- /dev/null
+++ b/doc/source/api/fixture.rst
@@ -0,0 +1,8 @@
+=========
+ fixture
+=========
+
+.. automodule:: oslo_versionedobjects.fixture
+   :members:
+   :undoc-members:
+
diff --git a/doc/source/installation.rst b/doc/source/installation.rst
index b02a051..7f29007 100644
--- a/doc/source/installation.rst
+++ b/doc/source/installation.rst
@@ -5,3 +5,8 @@
 At the command line::
 
     $ pip install oslo.versionedobjects
+
+To use ``oslo_versionedobjects.fixture``, some additional dependencies
+are needed. They can be installed using the ``fixtures`` extra::
+
+    $ pip install 'oslo.versionedobjects[fixtures]'
diff --git a/oslo_versionedobjects/fixture.py b/oslo_versionedobjects/fixture.py
index ea024d7..1689d0d 100644
--- a/oslo_versionedobjects/fixture.py
+++ b/oslo_versionedobjects/fixture.py
@@ -9,6 +9,16 @@
 #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #    License for the specific language governing permissions and limitations
 #    under the License.
+"""Fixtures for writing tests for code using oslo.versionedobjects
+
+.. note::
+
+   This module has several extra dependencies not needed at runtime
+   for production code, and therefore not installed by default. To
+   ensure those dependencies are present for your tests, add
+   ``oslo.versionedobjects[fixtures]`` to your list of test dependencies.
+
+"""
 
 from collections import OrderedDict
 import hashlib
diff --git a/requirements.txt b/requirements.txt
index 6be0d2c..c439190 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,7 +12,4 @@ oslo.utils>=1.6.0 # Apache-2.0
 iso8601>=0.1.9
 oslo.log>=1.2.0 # Apache-2.0
 oslo.i18n>=1.5.0 # Apache-2.0
-mock>=1.1;python_version!='2.6'
-mock==1.0.1;python_version=='2.6'
-fixtures>=1.3.1
 WebOb>=1.2.3
diff --git a/setup.cfg b/setup.cfg
index 6664bdf..f847599 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -22,6 +22,12 @@ classifier =
 packages =
     oslo_versionedobjects
 
+[extras]
+fixtures =
+  mock>=1.1:python_version!='2.6'
+  mock==1.0.1:python_version=='2.6'
+  fixtures>=1.3.1
+
 [pbr]
 warnerrors = true
 
diff --git a/tox.ini b/tox.ini
index 9bc33f5..7cdc7b6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,7 +12,7 @@ envlist = py34,py27,pypy,pep8
 install_command = pip install -U {opts} {packages}
 setenv =
    VIRTUAL_ENV={envdir}
-deps = -r{toxinidir}/requirements.txt
+deps = .[fixtures]
        -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
 
@@ -45,4 +45,4 @@ import_exceptions = oslo_versionedobjects._i18n
 # this also means that pip-missing-reqs must be installed separately, outside
 # of the requirements.txt files
 deps = pip_missing_reqs
-commands = pip-missing-reqs -d --ignore-module=oslo_versionedobjects* --ignore-module=pkg_resources --ignore-file=oslo_versionedobjects/test.py --ignore-file=oslo_versionedobjects/tests/* oslo_versionedobjects
\ No newline at end of file
+commands = pip-missing-reqs -d --ignore-module=oslo_versionedobjects* --ignore-module=pkg_resources --ignore-file=oslo_versionedobjects/test.py --ignore-file=oslo_versionedobjects/tests/* oslo_versionedobjects