diff --git a/sgsn/SGSN_Tests_Iu.ttcn b/sgsn/SGSN_Tests_Iu.ttcn
index 64d829d..472774e 100644
--- a/sgsn/SGSN_Tests_Iu.ttcn
+++ b/sgsn/SGSN_Tests_Iu.ttcn
@@ -15,7 +15,7 @@
 	var PdpActPars apars := valueof(t_PdpActPars(mp_ggsn_ip));
 
 	/* first perform regular attach */
-	f_gmm_attach(umts_aka_challenge := true, force_gsm_sres := false, gb_idx := 3);
+	f_gmm_attach(umts_aka_challenge := true, force_gsm_sres := false, ran_index := 3);
 	setverdict(pass);
 }
 testcase TC_iu_attach() runs on test_CT {
@@ -40,7 +40,7 @@
 	var PdpActPars apars := valueof(t_PdpActPars(mp_ggsn_ip));
 
 	/* first perform regular attach */
-	f_gmm_attach(umts_aka_challenge := true, force_gsm_sres := false, gb_idx := 3);
+	f_gmm_attach(umts_aka_challenge := true, force_gsm_sres := false, ran_index := 3);
 
 	/* do a routing area update */
 	f_routing_area_update(g_pars.ra);
@@ -63,7 +63,7 @@
 	var PdpActPars apars := valueof(t_PdpActPars(mp_ggsn_ip));
 
 	/* first perform regular attach */
-	f_gmm_attach(umts_aka_challenge := true, force_gsm_sres := false, gb_idx := 0);
+	f_gmm_attach(umts_aka_challenge := true, force_gsm_sres := false, ran_index := 0);
 
 	/* do a routing area update */
 	f_routing_area_update(g_pars.ra, bssgp := 3);