diff --git a/tools/ssl_cleanup b/tools/ssl_cleanup
index 5adfa1be..fd246eba 100755
--- a/tools/ssl_cleanup
+++ b/tools/ssl_cleanup
@@ -2,7 +2,7 @@
 # Cleanup SSL certificates which expired more than 7 days ago from $STORAGE_ROOT/ssl and move them to $STORAGE_ROOT/ssl.expired
 
 source /etc/mailinabox.conf
-shopt -s extglob
+shopt -s extglob nullglob
 
 retain_after="$(date --date="7 days ago" +%Y%m%d)"