diff --git a/requirements.txt b/requirements.txt
index d8956a9..44a0aaf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -27,3 +27,4 @@ tqdm
 virtualenv
 weasyprint; python_version>='3.5'
 xmltodict
+pillow>=8.1.0 # not directly required, pinned by Snyk to avoid a vulnerability