diff --git a/include/types/connection.h b/include/types/connection.h
index 0e12bb5..b74c71a 100644
--- a/include/types/connection.h
+++ b/include/types/connection.h
@@ -75,6 +75,8 @@
 	/* below we have all handshake flags grouped into one */
 	CO_FL_HANDSHAKE     = CO_FL_SI_SEND_PROXY,
 
+	CO_FL_INIT_SESS     = 0x00000800,  /* initialize a session before using data */
+
 	/* when any of these flags is set, polling is defined by socket-layer
 	 * operations, as opposed to data-layer.
 	 */
diff --git a/include/types/session.h b/include/types/session.h
index cce55a4..0450163 100644
--- a/include/types/session.h
+++ b/include/types/session.h
@@ -50,7 +50,7 @@
 #define SN_FORCE_PRST	0x00000010	/* force persistence here, even if server is down */
 #define SN_MONITOR	0x00000020	/* this session comes from a monitoring system */
 #define SN_CURR_SESS	0x00000040	/* a connection is currently being counted on the server */
-/* unused: 0x00000080 */
+#define SN_INITIALIZED	0x00000080	/* the session was fully initialized */
 #define SN_REDISP	0x00000100	/* set if this session was redispatched from one server to another */
 #define SN_CONN_TAR	0x00000200	/* set if this session is turning around before reconnecting */
 #define SN_REDIRECTABLE	0x00000400	/* set if this session is redirectable (GET or HEAD) */