diff --git a/artiq/protocols/pc_rpc.py b/artiq/protocols/pc_rpc.py
index 7f6140ecd..962fe10de 100644
--- a/artiq/protocols/pc_rpc.py
+++ b/artiq/protocols/pc_rpc.py
@@ -191,7 +191,7 @@ class AsyncioClient:
         this method is a coroutine. See ``Client`` for a description of the
         parameters."""
         self.__reader, self.__writer = \
-            await asyncio.open_connection(host, port)
+            await asyncio.open_connection(host, port, limit=4*1024*1024)
         try:
             self.__writer.write(_init_string)
             server_identification = await self.__recv()