diff --git a/src/python/grpcio/grpc/experimental/aio/_channel.py b/src/python/grpcio/grpc/experimental/aio/_channel.py
index 24692559c69..4abb6d69780 100644
--- a/src/python/grpcio/grpc/experimental/aio/_channel.py
+++ b/src/python/grpcio/grpc/experimental/aio/_channel.py
@@ -47,7 +47,7 @@ class _OngoingCalls:
         self._calls.remove(call)
 
     @property
-    def calls(self) -> Set[_base_call.RpcContext]:
+    def calls(self) -> AbstractSet[_base_call.RpcContext]:
         """Returns the set of ongoing calls."""
         return self._calls