diff --git a/library/GTPv2_Emulation.ttcn b/library/GTPv2_Emulation.ttcn
index 807426949..f07afcb14 100644
--- a/library/GTPv2_Emulation.ttcn
+++ b/library/GTPv2_Emulation.ttcn
@@ -359,6 +359,7 @@ runs on GTPv2_Emulation_CT  return PDU_UECUPS {
 	var UECUPS_RecvFrom mrf;
 
 	UECUPS.send(t_UECUPS_Send(g_uecups_conn_id, tx));
+	T.start;
 	alt {
 	[] UECUPS.receive(tr_UECUPS_RecvFrom_R(rx_t)) -> value mrf { }
 	[] UECUPS.receive(tr_SctpAssocChange) { repeat; }