diff --git a/source/requirements.txt b/source/requirements.txt
index 5da928611..d22f01a34 100644
--- a/source/requirements.txt
+++ b/source/requirements.txt
@@ -1,2 +1,3 @@
 Pelican==3.5.0
 Markdown==2.6.1
+pygments>=2.7.4 # not directly required, pinned by Snyk to avoid a vulnerability