diff --git a/nvim/msgpack_rpc_stream.lua b/nvim/msgpack_rpc_stream.lua
index faa808a..b3f99ca 100644
--- a/nvim/msgpack_rpc_stream.lua
+++ b/nvim/msgpack_rpc_stream.lua
@@ -133,7 +133,7 @@ function MsgpackRpcStream:read_start(request_cb, notification_cb, eof_cb)
           notification_cb(method_or_error, args_or_result)
         end
       elseif type == 'response' then
-        self._previous_chunk = string.format('response<%s>', args_or_result)
+        self._previous_chunk = string.format('response<#%d>', #args_or_result)
         if method_or_error == mpack.NIL then
           method_or_error = nil
         else