diff --git a/requirements_dev.txt b/requirements_dev.txt
index 8893b49..2d92c1a 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -9,3 +9,4 @@ bump2version
 twine
 mock
 tornado>=6.3.3  # not directly required, pinned by Snyk to avoid a vulnerability
+waitress>=3.0.1 # not directly required, pinned by Snyk to avoid a vulnerability