diff --git a/tox.ini b/tox.ini
index e2ac7e13..b3a08acd 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,7 +7,7 @@ sitepackages=False
 stxdir = {toxinidir}/..
 
 [testenv]
-install_command = pip install \
+install_command = pip install --use-deprecated legacy-resolver\
     -v -v -v \
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/stable/stein/upper-constraints.txt} \
     -U {opts} {packages}