diff --git a/lib/fluent/event.rb b/lib/fluent/event.rb
index b316da073f..2fe2a2525d 100644
--- a/lib/fluent/event.rb
+++ b/lib/fluent/event.rb
@@ -87,6 +87,10 @@ def dup
       OneEventStream.new(@time, @record.dup)
     end
 
+    def empty?
+      false
+    end
+
     def size
       1
     end