diff --git a/WORKSPACE b/WORKSPACE
index 8cb819517d..86377227f8 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -98,6 +98,9 @@ git_repository(
 )
 
 ## Protobuf
+# proto_library, cc_proto_library, and java_proto_library rules implicitly
+# depend on @com_google_protobuf for protoc and proto runtimes.
+# This statement defines the @com_google_protobuf repo.
 git_repository(
     name = "com_google_protobuf",
     tag = "v25.0",