diff --git a/requirements.txt b/requirements.txt
index eb632a0..c6336a8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,6 +9,9 @@ isodate
 # flask 2.3 does not provide flask.json.JSONEncoder anymore
 # (can be replaced by vanilla json encoder, but our code is not updated (yet?)
 flask==2.2.3
+# https://stackoverflow.com/a/77217971
+# current version 3.0 does not work with (older) Flask
+Werkzeug==2.2.2
 psutil
 fastapi
 uvicorn[standard]