diff --git a/tox.ini b/tox.ini
index ebe29401..7038b092 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,7 +5,7 @@ skipsdist = True
 
 [testenv]
 install_command = pip install \
-    -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/stable/stein/upper-constraints.txt} \
+    -chttps://opendev.org/openstack/requirements/raw/branch/stable/stein/upper-constraints.txt \
     {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
          OS_STDOUT_CAPTURE=1