diff --git a/requirements.txt b/requirements.txt
index 589c420..b6dc88b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,3 +5,4 @@ django-phonenumber-field==6.1.0
 twilio>=7
 wheel>=0.22.0
 setuptools>=36.2
+zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability