diff --git a/iam/go_mod_tidy_hack.go b/iam/go_mod_tidy_hack.go
index fbdd65f60c0..c3f49e045d2 100644
--- a/iam/go_mod_tidy_hack.go
+++ b/iam/go_mod_tidy_hack.go
@@ -14,6 +14,7 @@
 
 // This file, and the cloud.google.com/go import, won't actually become part of
 // the resultant binary.
+//go:build modhack
 // +build modhack
 
 package iam