diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index cbb77c5e0..bf07147d6 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -52,6 +52,10 @@ interpreter of one of supported versions (currently 2.7 and 3.4), use
     Support for Python 3 is highly experimental, stay with Python 2 for the
     production environment for now.
 
+.. note::
+    Users of Fedora <= 23 will need to run "sudo dnf --releasever=24 update
+    python-virtualenv" to run unit tests
+
 There is a simple functional test that involves fetching the ramdisk from
 Github::
 
diff --git a/tox.ini b/tox.ini
index 6e5939cf4..0114e3a81 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,6 +3,7 @@ envlist = py27,py34,pep8,func
 
 [testenv]
 usedevelop = True
+install_command = pip install -U -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=stable/liberty} {opts} {packages}
 deps =
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/test-requirements.txt
@@ -14,9 +15,21 @@ setenv = PYTHONDONTWRITEBYTECODE=1
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:venv]
+# NOTE(amrith) The setting of the install_command in this location
+# is only required because currently infra does not actually
+# support constraints files for the environment job, and while
+# the environment variable UPPER_CONSTRAINTS_FILE is set, there's
+# no file there. It can be removed when infra changes this.
+install_command = pip install -U {opts} {packages}
 commands = {posargs}
 
 [testenv:releasenotes]
+# NOTE(amrith) The setting of the install_command in this location
+# is only required because currently infra does not actually
+# support constraints files for the release notes job, and while
+# the environment variable UPPER_CONSTRAINTS_FILE is set, there's
+# no file there. It can be removed when infra changes this.
+install_command = pip install -U {opts} {packages}
 envdir = {toxworkdir}/venv
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html