diff --git a/lib/fluent/plugin/in_tail.rb b/lib/fluent/plugin/in_tail.rb
index b31d88e7a2..deea7c9498 100644
--- a/lib/fluent/plugin/in_tail.rb
+++ b/lib/fluent/plugin/in_tail.rb
@@ -511,7 +511,7 @@ def update_watcher(target_info, pe)
         if new_position_entry.read_inode == 0
           # When follow_inodes is true, it's not cleaned up by refresh_watcher.
           # So it should be unwatched here explicitly.
-          rotated_tw.unwatched = true
+          rotated_tw.unwatched = true if rotated_tw
           @tails[path] = setup_watcher(target_info, new_position_entry)
           @tails[path].on_notify
         end