diff --git a/test/test_supervisor.rb b/test/test_supervisor.rb
index 5890cbcac3..dccd3cc781 100644
--- a/test/test_supervisor.rb
+++ b/test/test_supervisor.rb
@@ -405,7 +405,7 @@ def test_supervisor_event_dump_windows
     # https://github.com/fluent/fluentd/issues/4063
     GC.start
 
-    ENV['SIGDUMP_PATH'] = TMP_DIR + "/sigdump.log"
+    ENV['SIGDUMP_PATH'] = @tmp_dir + "/sigdump.log"
 
     server = DummyServer.new
     def server.config
@@ -423,7 +423,7 @@ def server.config
       server.stop_windows_event_thread
     end
 
-    result_filepaths = Dir.glob("#{TMP_DIR}/*")
+    result_filepaths = Dir.glob("#{@tmp_dir}/*")
     assert {result_filepaths.length > 0}
   ensure
     ENV.delete('SIGDUMP_PATH')