diff --git a/include/types/hlua.h b/include/types/hlua.h
index 74dcf00..e8daf53 100644
--- a/include/types/hlua.h
+++ b/include/types/hlua.h
@@ -156,6 +156,7 @@
 struct hlua_socket {
 	struct xref xref; /* cross reference with the stream used for socket I/O. */
 	luaL_Buffer b; /* buffer used to prepare strings. */
+	unsigned long tid; /* Store the thread id which creates the socket. */
 };
 
 struct hlua_concat {