diff --git a/optional-requirements.txt b/optional-requirements.txt
index 87c8380e..b478b9b4 100644
--- a/optional-requirements.txt
+++ b/optional-requirements.txt
@@ -38,3 +38,4 @@ sparklines
 statsd
 uvicorn
 zeroconf
+h11>=0.16.0 # not directly required, pinned by Snyk to avoid a vulnerability