diff --git a/requirements.txt b/requirements.txt
index bbf537d..9c58cd3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,3 +3,5 @@
 xnat>=0.3.9
 progressbar2>=3.16.0
 future>=0.16
+pygments>=2.7.4 # not directly required, pinned by Snyk to avoid a vulnerability
+sphinx>=3.0.4 # not directly required, pinned by Snyk to avoid a vulnerability