diff --git a/test/plugin/test_parser_regexp.rb b/test/plugin/test_parser_regexp.rb
index 7fc5a98604..b5a5c5fb30 100644
--- a/test/plugin/test_parser_regexp.rb
+++ b/test/plugin/test_parser_regexp.rb
@@ -28,12 +28,7 @@ def create_driver(regexp, conf = {}, initialize_conf: false)
       if initialize_conf
         Fluent::Test::Driver::Parser.new(Fluent::Compat::TextParser::RegexpParser.new(regexp, conf))
       else
-        # Fluent::Test::Driver::Parser.new(Fluent::Compat::TextParser::RegexpParser.new(regexp)).configure(conf)
-        instance = Fluent::Compat::TextParser::RegexpParser.new(regexp)
-        instance.configure(conf)
-        d = Struct.new(:instance).new
-        d.instance = instance
-        d
+        Fluent::Test::Driver::Parser.new(Fluent::Compat::TextParser::RegexpParser.new(regexp)).configure(conf)
       end
     end