diff --git a/tox.ini b/tox.ini
index 84288ac..0357667 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,7 +11,7 @@ setenv = VIRTUAL_ENV={envdir}
          NOSE_OPENSTACK_RED=0.05
          NOSE_OPENSTACK_YELLOW=0.025
          NOSE_OPENSTACK_SHOW_ELAPSED=1
-install_command = pip install -U {opts} {packages}
+install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} -U {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
        http://tarballs.openstack.org/horizon/horizon-master.tar.gz