diff --git a/tox.ini b/tox.ini
index 5f040e6..68bc57f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,7 +6,7 @@ ignore_basepython_conflict = true
 [testenv]
 basepython = python3
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/ussuri}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 # Functional tests with Eventlet involve monkeypatching, so force them to be
@@ -18,7 +18,7 @@ commands =
 
 [testenv:pep8]
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/ussuri}
   -r{toxinidir}/test-requirements.txt
 commands =
   flake8
@@ -42,7 +42,7 @@ commands = {posargs}
 [testenv:docs]
 whitelist_externals = rm
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/ussuri}
   -r{toxinidir}/doc/requirements.txt
 commands =
   rm -fr doc/build
@@ -65,7 +65,7 @@ commands = python3 benchmark/benchmark.py
 [testenv:releasenotes]
 whitelist_externals = rm
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/ussuri}
   -r{toxinidir}/doc/requirements.txt
 commands =
   rm -rf releasenotes/build