diff --git a/rslib/build.rs b/rslib/build.rs
index ef384d339..caa65d082 100644
--- a/rslib/build.rs
+++ b/rslib/build.rs
@@ -23,7 +23,8 @@ fn get_identifiers(ftl_text: &str) -> Vec<String> {
 
 fn proto_enum(idents: &[String]) -> String {
     let mut buf = String::from(
-        r#"
+        r#"// This file is automatically generated as part of the build process.
+
 syntax = "proto3";
 package backend_proto;
 enum FluentString {
@@ -67,7 +68,8 @@ mod test {
 
         assert_eq!(
             proto_enum(&idents),
-            r#"
+            r#"// This file is automatically generated as part of the build process.
+
 syntax = "proto3";
 package backend_strings;
 enum FluentString {