diff --git a/tox.ini b/tox.ini
index 87a3cd3700..5392db0fe3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,7 +6,7 @@ skipsdist = True
 [testenv]
 usedevelop = True
 install_command =
-  pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} -U {opts} {packages}
+  pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 whitelist_externals = bash
                       find
                       rm