diff --git a/sample-go-mod/tools.go b/sample-go-mod/tools.go
index 224c27f..9660590 100644
--- a/sample-go-mod/tools.go
+++ b/sample-go-mod/tools.go
@@ -1,4 +1,4 @@
-// +build tools
+//go:build tools
 
 package main