diff --git a/tox.ini b/tox.ini
index a99de82d..35bb1284 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,6 +14,7 @@ deps =
   cryptography
   python-dateutil
   flask21: Flask>=2.1,<2.2
+  flask21: Werkzeug>=2,<3
 
 [testenv:mypy]
 commands =