diff --git a/tox.ini b/tox.ini
index 0e0c3133a8..a6eac220cd 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,7 +10,7 @@ allowlist_externals =
   rm
   env
   make
-install_command = python -I -m pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
+install_command = python -I -m pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2026.1} {opts} {packages}
 setenv =
   VIRTUAL_ENV={envdir}
   LANGUAGE=en_US