--- a/mod_storage_s3/mod_storage_s3.lua	Wed Nov 22 11:54:22 2023 +0000
+++ b/mod_storage_s3/mod_storage_s3.lua	Wed Nov 22 12:56:50 2023 +0100
@@ -206,8 +206,8 @@
 		bucket;
 		jid.escape(module.host);
 		jid.escape(self.store);
-		jid.escape(username);
-		jid.escape(jid.prep(with));
+		jid.escape(username or "@");
+		jid.escape(with and jid.prep(with) or "@");
 		date or dt.date(when);
 		key;
 	})