diff --git a/tractor/_clustering.py b/tractor/_clustering.py
index 829caff..8142373 100644
--- a/tractor/_clustering.py
+++ b/tractor/_clustering.py
@@ -2,6 +2,8 @@
 Actor cluster helpers.
 
 '''
+from __future__ import annotations
+
 from contextlib import asynccontextmanager as acm
 from multiprocessing import cpu_count
 from typing import AsyncGenerator, Optional