diff --git a/lualib/skynet/db/mysql.lua b/lualib/skynet/db/mysql.lua
index cb67f7dc..6ac2797d 100644
--- a/lualib/skynet/db/mysql.lua
+++ b/lualib/skynet/db/mysql.lua
@@ -463,7 +463,7 @@ local function _mysql_login(self, user, password, charset, database, on_connect)
             client_flags,
             self._max_packet_size,
             strchar(charset),
-            strrep("\0", 23), -- TODO: add support for charset encoding
+            strrep("\0", 23),
             user,
             token,
             database