diff --git a/src/vnet/devices/virtio/virtio.h b/src/vnet/devices/virtio/virtio.h
index 90eeb53..7ffb2ea 100644
--- a/src/vnet/devices/virtio/virtio.h
+++ b/src/vnet/devices/virtio/virtio.h
@@ -132,6 +132,8 @@
 				 u32 idx);
 extern void virtio_free_used_desc (vlib_main_t * vm, virtio_vring_t * vring);
 
+format_function_t format_virtio_device_name;
+
 #endif /* _VNET_DEVICES_VIRTIO_VIRTIO_H_ */
 
 /*