diff --git a/src/main_udt.c b/src/main_udt.c
index 385f3f5..b47ea66 100644
--- a/src/main_udt.c
+++ b/src/main_udt.c
@@ -186,6 +186,7 @@
 	bsc.dpc = 1;
 	bsc.opc = 0;
 	bsc.sccp_opc = -1;
+	bsc.isup_opc = -1;
 	bsc.udp_port = 3456;
 	bsc.udp_ip = NULL;
 	bsc.src_port = 1313;