diff --git a/src/vat2/test/vat2_test.api b/src/vat2/test/vat2_test.api
index afc8afa..6d21155 100644
--- a/src/vat2/test/vat2_test.api
+++ b/src/vat2/test/vat2_test.api
@@ -14,6 +14,7 @@
  */
 
 import "vnet/ip/ip_types.api";
+import "vnet/interface_types.api";
 
 autoreply define test_prefix {
   vl_api_prefix_t pref;
@@ -94,3 +95,8 @@
   u32 client_index;
   u32 context;
 };
+
+/* Interface */
+autoreply define test_interface {
+  vl_api_interface_index_t sw_if_index;
+};