diff --git a/pjsip/include/pjsua-lib/pjsua_internal.h b/pjsip/include/pjsua-lib/pjsua_internal.h
index caba46a..527b53a 100644
--- a/pjsip/include/pjsua-lib/pjsua_internal.h
+++ b/pjsip/include/pjsua-lib/pjsua_internal.h
@@ -252,6 +252,7 @@
     pjsip_endpoint	*endpt;	    /**< Global endpoint.		*/
     pjsip_module	 mod;	    /**< pjsua's PJSIP module.		*/
     pjsua_transport_data tpdata[8]; /**< Array of transports.		*/
+    pjsip_tp_state_callback old_tp_cb; /**< Old transport callback.	*/
 
     /* Threading: */
     pj_bool_t		 thread_quit_flag;  /**< Thread quit flag.	*/