diff --git a/test/plugin/test_out_file.rb b/test/plugin/test_out_file.rb
index a87ab7b9d8..562329d255 100644
--- a/test/plugin/test_out_file.rb
+++ b/test/plugin/test_out_file.rb
@@ -558,9 +558,7 @@ def parse_system(text)
   end
 
   test 'append when JST' do
-    p ["TZ 1", ENV["TZ"]]
-    with_timezone("JST") do
-      p ["TZ 2", ENV["TZ"]]
+    with_timezone("Asia/Tokyo") do
       time = event_time("2011-01-02 03:14:15+09:00")
       formatted_lines = %[2011-01-02T03:14:15+09:00\ttest\t{"a":1}\n] + %[2011-01-02T03:14:15+09:00\ttest\t{"a":2}\n]