diff --git a/msc_tests/MSC_Tests.ttcn b/msc_tests/MSC_Tests.ttcn
index 367cd79..74d1b93 100644
--- a/msc_tests/MSC_Tests.ttcn
+++ b/msc_tests/MSC_Tests.ttcn
@@ -331,7 +331,8 @@
 		msisdn := f_gen_msisdn(imsi_suffix),
 		tmsi := omit,
 		cm2 := valueof(ts_CM2_default),
-		cm3 := omit
+		cm3 := omit,
+		kc := omit
 	};
 
 	vc_conn := BSC_ConnHdlr.create(id);
@@ -1087,6 +1088,21 @@
 	vc_conn.done;
 }
 
+private function f_tc_lu_imsi_auth_tmsi_encr_13_13(charstring id, BSC_ConnHdlrPars pars) runs on BSC_ConnHdlr {
+	g_pars := pars;
+	f_perform_lu(true, true, true, true);
+}
+testcase TC_lu_imsi_auth_tmsi_encr_13_13() runs on MTC_CT {
+	var BSC_ConnHdlr vc_conn;
+	f_init();
+	f_vty_config(MSCVTY, "network", "authentication required");
+	f_vty_config(MSCVTY, "msc", "assign-tmsi");
+	f_vty_config(MSCVTY, "network", "encryption a5 1 3");
+
+	vc_conn := f_start_handler(refers(f_tc_lu_imsi_auth_tmsi_encr_13_13), testcasename(), 24);
+	vc_conn.done;
+}
+
 
 /* TODO:
    * continue to send repeated MO signalling messages to keep channel open: does MSC tmeout?