diff --git a/docs/requirements.txt b/docs/requirements.txt
index f9713f94b2..e662625e8d 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -3,3 +3,4 @@ Cython
 matplotlib
 numpy
 Pillow
+fonttools>=4.43.0 # not directly required, pinned by Snyk to avoid a vulnerability