diff --git a/tox.ini b/tox.ini
index 5883913..72ad4c0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,7 +7,9 @@ skipsdist = True
 client_base_dir = .
 
 [testenv]
-install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/upper-constraints.txt} {opts} {packages}
+install_command = pip install \
+    -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/stable/stein/upper-constraints.txt} \
+    {opts} {packages}
 setenv =
     VIRTUAL_ENV={envdir}
     OS_STDOUT_CAPTURE=1