diff --git a/tests/sample-sites/python-flask/requirements.txt b/tests/sample-sites/python-flask/requirements.txt
index 78e963f..c90c4cf 100644
--- a/tests/sample-sites/python-flask/requirements.txt
+++ b/tests/sample-sites/python-flask/requirements.txt
@@ -3,5 +3,5 @@ Flask==1.1.1
 itsdangerous==1.1.0
 Jinja2==2.10.1
 MarkupSafe==1.1.1
-waitress==1.4.3
+waitress==2.1.1
 Werkzeug==0.15.5