diff --git a/src/vnet/vxlan-gbp/vxlan_gbp.api b/src/vnet/vxlan-gbp/vxlan_gbp.api
index 40d61a5..c3a8845 100644
--- a/src/vnet/vxlan-gbp/vxlan_gbp.api
+++ b/src/vnet/vxlan-gbp/vxlan_gbp.api
@@ -69,7 +69,7 @@
 {
   u32 client_index;
   u32 context;
-  vl_api_interface_index_t sw_if_index;
+  vl_api_interface_index_t sw_if_index [default=0xffffffff];
 };
 
 define vxlan_gbp_tunnel_details