diff --git a/.gitreview b/.gitreview
index 45314a6..4c45004 100644
--- a/.gitreview
+++ b/.gitreview
@@ -2,4 +2,4 @@
 host=review.opendev.org
 port=29418
 project=openstack/python-observabilityclient.git
-defaultbranch=master
+defaultbranch=stable/2026.1
diff --git a/tox.ini b/tox.ini
index 36238a2..49b8f3c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,7 +12,7 @@ passenv =
   PROMETHEUS_*
   OBSERVABILITY_*
 deps =
-  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2026.1}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
 commands = stestr run --slowest --test-path {env:OS_TEST_PATH} {posargs}
@@ -51,7 +51,7 @@ commands =
 
 [testenv:docs]
 deps =
-  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/2026.1}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build --keep-going -b html doc/source doc/build/html