diff --git a/sgsn/SGSN_Tests_Iu.ttcn b/sgsn/SGSN_Tests_Iu.ttcn
index 5f1bb55..0a589b9 100644
--- a/sgsn/SGSN_Tests_Iu.ttcn
+++ b/sgsn/SGSN_Tests_Iu.ttcn
@@ -4,6 +4,7 @@
 import from Osmocom_VTY_Functions all;
 
 import from SGSN_Tests all;
+import from BSSGP_Emulation all;
 
 import from RAN_Adapter all;
 import from RAN_Emulation all;
@@ -71,6 +72,10 @@
 	/* first perform regular attach */
 	f_gmm_attach(umts_aka_challenge := true, force_gsm_sres := false, ran_index := 3);
 
+	/* we got a new TLLI, register it */
+	f_bssgp_client_unregister(g_pars.imsi);
+	f_bssgp_client_register(g_pars.imsi, g_pars.tlli);
+
 	/* do a routing area update */
 	f_routing_area_update(g_pars.ra);
 }