diff --git a/asyncpg/pool.py b/asyncpg/pool.py
index 20a3234e..b592f03c 100644
--- a/asyncpg/pool.py
+++ b/asyncpg/pool.py
@@ -767,7 +767,7 @@ def __init__(self, pool, timeout):
         self.connection = None
         self.done = False
 
-    async def __aenter__(self):
+    async def __aenter__(self) -> connection.Connection:
         if self.connection is not None or self.done:
             raise exceptions.InterfaceError('a connection is already acquired')
         self.connection = await self.pool._acquire(self.timeout)