diff --git a/bar_option.go b/bar_option.go
index 2ffa497..f07268f 100644
--- a/bar_option.go
+++ b/bar_option.go
@@ -121,8 +121,9 @@
 	if filler == nil {
 		return nil
 	}
-	return func(s *bState) {
-		s.extender = makeExtenderFunc(filler, rev)
+	fn := makeExtenderFunc(filler, rev)
+	return func(s *bState) {
+		s.extender = fn
 	}
 }