diff --git a/tox.ini b/tox.ini
index 9efa55cfa..f7115687b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -17,7 +17,7 @@ commands =
 # mode. To do this define the TRACE_FAILONLY environmental variable.
 
 [testenv:common-constraints]
-install_command = {toxinidir}/tools/tox_install.sh constrained -c{env:UPPER_CONTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
+install_command = {toxinidir}/tools/tox_install.sh constrained -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 
 [tox:jenkins]
 sitepackages = True