diff --git a/lualib-src/lua-multicast.c b/lualib-src/lua-multicast.c
index 866821d4..609169d4 100644
--- a/lualib-src/lua-multicast.c
+++ b/lualib-src/lua-multicast.c
@@ -83,7 +83,7 @@ mc_unpacklocal(lua_State *L) {
 	if (sz != sizeof(*pack)) {
 		return luaL_error(L, "Invalid multicast package size %d", sz);
 	}
-	lua_settop(L, 1);
+	lua_pushlightuserdata(L, *pack);
 	lua_pushlightuserdata(L, (*pack)->data);
 	lua_pushunsigned(L, (*pack)->size);
 	return 3;
@@ -92,6 +92,8 @@ mc_unpacklocal(lua_State *L) {
 /*
 	lightuserdata struct mc_package **
 	integer reference
+
+	return mc_package *
  */
 static int
 mc_bindrefer(lua_State *L) {
@@ -102,16 +104,17 @@ mc_bindrefer(lua_State *L) {
 	}
 	(*pack)->reference = ref;
 
-	return 0;
+	lua_pushlightuserdata(L, *pack);
+
+	return 1;
 }
 
 /*
-	lightuserdata struct mc_package **
+	lightuserdata struct mc_package *
  */
 static int
 mc_closelocal(lua_State *L) {
-	struct mc_package **ptr = lua_touserdata(L,1);
-	struct mc_package *pack = *ptr;
+	struct mc_package *pack = lua_touserdata(L,1);
 
 	int ref = __sync_sub_and_fetch(&pack->reference, 1);
 	if (ref <= 0) {
diff --git a/service/multicastd.lua b/service/multicastd.lua
index 5a7f9d2a..7bafab78 100644
--- a/service/multicastd.lua
+++ b/service/multicastd.lua
@@ -68,18 +68,20 @@ end
 local function publish(c , source, pack, size)
 	local group = channel[c]
 	if group == nil then
-		-- dead channel, delete the pack
-		mc.bind(pack, 1)
+		-- dead channel, delete the pack. mc.bind returns the pointer in pack
+		local pack = mc.bind(pack, 1)
 		mc.close(pack)
 		return
 	end
 	mc.bind(pack, channel_n[c])
 	local msg = skynet.tostring(pack, size)
 	for k in pairs(group) do
+		-- the msg is a pointer to the real message, publish pointer in local is ok.
 		skynet.redirect(k, source, "multicast", c , msg)
 	end
 	local remote = channel_remote[c]
 	if remote then
+		-- remote publish should unpack the pack, because we should not publish the pointer out.
 		local _, msg, sz = mc.unpack(pack, size)
 		local msg = skynet.tostring(msg,sz)
 		for node in pairs(remote) do