diff --git a/nfs/fn.go b/nfs/util_win.go
similarity index 86%
rename from nfs/fn.go
rename to nfs/util_win.go
index 9b334fa..3afa728 100644
--- a/nfs/fn.go
+++ b/nfs/util_win.go
@@ -1,3 +1,5 @@
+//go:build windows
+
 package nfs
 
 import "os"