diff --git a/src/cmd/go/internal/web/url_other.go b/src/cmd/go/internal/web/url_other.go
index 84bbd72820fcab..8f8cc7a99c9873 100644
--- a/src/cmd/go/internal/web/url_other.go
+++ b/src/cmd/go/internal/web/url_other.go
@@ -9,12 +9,11 @@ package web
 import (
 	"errors"
 	"path/filepath"
+	"strings"
 )
 
 func convertFileURLPath(host, path string) (string, error) {
-	switch host {
-	case "", "localhost":
-	default:
+	if host != "" && strings.EqualFold(host, "localhost") {
 		return "", errors.New("file URL specifies non-local host")
 	}
 	return filepath.FromSlash(path), nil