diff --git a/examples/server/tornado/requirements.txt b/examples/server/tornado/requirements.txt
index 354f4a7a..b41af485 100644
--- a/examples/server/tornado/requirements.txt
+++ b/examples/server/tornado/requirements.txt
@@ -2,3 +2,4 @@ tornado==5.0.2
 python-engineio
 python_socketio
 six==1.10.0
+h11>=0.16.0 # not directly required, pinned by Snyk to avoid a vulnerability