diff --git a/requirements.txt b/requirements.txt
index fafc6a0..a3acbc9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,3 +3,4 @@ Sphinx==1.6.3
 model-mommy==1.5.1
 requests==2.18.4
 pyqt5==5.10.1
+pygments>=2.7.4 # not directly required, pinned by Snyk to avoid a vulnerability