diff --git a/setup.py b/setup.py
index 37eb34e9..ed052914 100644
--- a/setup.py
+++ b/setup.py
@@ -43,7 +43,7 @@
     install_requires=requires,
     extras_require={
         "email": ["pydantic[email]>=1.2"],
-        "flask": ["flask"],
+        "flask": ["flask", "werkzeug<2.2"],
         "falcon": ["falcon"],
         "starlette": ["starlette[full]"],
         "dev": [