diff --git a/lib/logstash/codecs/netflow.rb b/lib/logstash/codecs/netflow.rb
index 3d86201..e02e307 100644
--- a/lib/logstash/codecs/netflow.rb
+++ b/lib/logstash/codecs/netflow.rb
@@ -647,7 +647,7 @@ def do_load
     # @see `TemplateRegistry#persist`
     # @api private
     def do_persist
-      return if file_path.nil?
+      (do_cleanup!; return) if file_path.nil?
 
       logger.debug? and logger.debug('Writing templates to template cache', :file_path => file_path)