diff --git a/tox.ini b/tox.ini
index 45e58ca88..5e923dfd0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -314,3 +314,5 @@ setenv = AWS_DEFAULT_REGION=us-east-1
 changedir = letstest
 deps = -e {toxinidir}/letstest
 commands = {toxinidir}/tools/retry.sh letstest targets/targets.yaml {env:AWS_EC2_PEM_FILE} SET_BY_ENV scripts/test_apache2.sh --repo {toxinidir}
+allowlist_externals =
+    {toxinidir}/tools/retry.sh