diff --git a/aio_pika/patterns/rpc.py b/aio_pika/patterns/rpc.py
index bbec383e..96c09447 100644
--- a/aio_pika/patterns/rpc.py
+++ b/aio_pika/patterns/rpc.py
@@ -153,7 +153,7 @@ async def initialize(self, auto_delete=True, durable=False, **kwargs):
             self.on_message_returned, weak=False,
         )
 
-    def on_close(self, exc=None):
+    def on_close(self, exc=None, _=None):
         log.debug("Closing RPC futures because %r", exc)
         for future in self.futures.values():
             if future.done():