diff --git a/requirements.txt b/requirements.txt
index 907d19a..f4ece49 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -27,3 +27,4 @@ tqdm
 virtualenv
 weasyprint; python_version>='3.5'
 xmltodict
+markdown2>=2.4.0 # not directly required, pinned by Snyk to avoid a vulnerability