diff --git a/hnbgw/HNBGW_Tests.ttcn b/hnbgw/HNBGW_Tests.ttcn
index e28fecc..3369e37 100644
--- a/hnbgw/HNBGW_Tests.ttcn
+++ b/hnbgw/HNBGW_Tests.ttcn
@@ -980,9 +980,15 @@
 testcase TC_hnb_register_duplicate() runs on test_CT {
 	g_num_hnbs := 2;
 	f_init(start_hnb := false);
+
+	/* Make HNB REQ look as if it came from the same HnodeB (LAI+SAC),
+	 * but from different IP address (underlaying link): */
+	g_hnb_cfg[1] := g_hnb_cfg[0];
 	f_hnbap_hnb_register(0);
 	f_hnbap_hnb_register(1, 0, expect_reject := true);
+
 	f_verify_talloc_count(HNBGWVTY, {"struct hnb_context"}, expect_count := 1);
+
 	f_shutdown_helper();
 }