diff --git a/api/BUILD b/api/BUILD
index 3e990fa9783a5..a70eae799d797 100644
--- a/api/BUILD
+++ b/api/BUILD
@@ -1,3 +1,5 @@
+# DO NOT EDIT. This file is generated by tools/proto_format/proto_sync.py.
+
 load("@rules_proto//proto:defs.bzl", "proto_library")
 
 licenses(["notice"])  # Apache 2