diff --git a/requirements.txt b/requirements.txt
index 2660abc..b05d791 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,3 +4,4 @@ scipy>=1.2.1
 matplotlib>=3.0.2
 xlrd>=1.2.0
 pillow>=10.3.0 # not directly required, pinned by Snyk to avoid a vulnerability
+fonttools>=4.61.0 # not directly required, pinned by Snyk to avoid a vulnerability