diff --git a/ns/NS_Tests.ttcn b/ns/NS_Tests.ttcn
index a19477d..8553684 100644
--- a/ns/NS_Tests.ttcn
+++ b/ns/NS_Tests.ttcn
@@ -752,6 +752,20 @@
 	f_clean_ns_codec();
 }
 
+/* Ensure a SNS SIZE ACK is transmitted from the correct port */
+testcase TC_sns_sgsn_size_correct_port() runs on RAW_Test_CT {
+	f_init_vty();
+	f_init_ns_codec(mp_nsconfig);
+	f_init_ns_codec(mp_nsconfig, 1);
+	f_outgoing_sns_size(max_nsvcs := 10);
+	f_outgoing_sns_config();
+	f_incoming_sns_config();
+	NSCP[0].receive(t_NS_ALIVE);
+	f_outgoing_sns_size(max_nsvcs := 10, idx := 1);
+	setverdict(pass);
+	f_clean_ns_codec();
+}
+
 testcase TC_sns_sgsn_add() runs on RAW_Test_CT {
 	g_handle_rx_alive := true;
 	f_init_vty();
@@ -900,6 +914,7 @@
 			execute( TC_sns_sgsn_add() );
 			execute( TC_sns_sgsn_del() );
 			execute( TC_sns_sgsn_add_change_del() );
+			execute( TC_sns_sgsn_size_correct_port() );
 		}
 	}
 }