diff --git a/lualib/skynet.lua b/lualib/skynet.lua
index 73a4d3e7..107b5a37 100644
--- a/lualib/skynet.lua
+++ b/lualib/skynet.lua
@@ -45,6 +45,7 @@ local skynet = {
 
 -- code cache
 skynet.cache = require "skynet.codecache"
+skynet._proto = proto
 
 function skynet.register_protocol(class)
 	local name = class.name