diff --git a/src/vnet/devices/af_packet/af_packet.c b/src/vnet/devices/af_packet/af_packet.c
index e286ae9..46bb42a 100644
--- a/src/vnet/devices/af_packet/af_packet.c
+++ b/src/vnet/devices/af_packet/af_packet.c
@@ -231,7 +231,9 @@
   p = mhash_get (&apm->if_index_by_host_if_name, host_if_name);
   if (p)
     {
-      return VNET_API_ERROR_SUBIF_ALREADY_EXISTS;
+      apif = vec_elt_at_index (apm->interfaces, p[0]);
+      *sw_if_index = apif->sw_if_index;
+      return VNET_API_ERROR_IF_ALREADY_EXISTS;
     }
 
   vec_validate (rx_req, 0);