diff --git a/hmp.h b/hmp.h
index 6c3bdcd..cc1ca58 100644
--- a/hmp.h
+++ b/hmp.h
@@ -54,6 +54,7 @@
 void hmp_balloon(Monitor *mon, const QDict *qdict);
 void hmp_block_resize(Monitor *mon, const QDict *qdict);
 void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict);
+void hmp_snapshot_blkdev_internal(Monitor *mon, const QDict *qdict);
 void hmp_drive_mirror(Monitor *mon, const QDict *qdict);
 void hmp_drive_backup(Monitor *mon, const QDict *qdict);
 void hmp_migrate_cancel(Monitor *mon, const QDict *qdict);