diff --git a/requirements.txt b/requirements.txt
index 4ab330f..512ca47 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,3 +3,4 @@ numpy>=1.18.*,<2
 scipy>=1.4.*,<2
 statsmodels>=0.11.*
 numpy-fracdiff>=0.3.1
+zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability