diff --git a/test/test_supervisor.rb b/test/test_supervisor.rb
index dccd3cc781..d4e2e8bfa6 100644
--- a/test/test_supervisor.rb
+++ b/test/test_supervisor.rb
@@ -353,6 +353,7 @@ def server.config
       event = Win32::Event.open("TestFluentdEvent")
       event.set
       event.close
+      sleep 1.0 # Wait for dumping
     ensure
       server.stop_windows_event_thread
     end
@@ -379,6 +380,7 @@ def server.config
       event = Win32::Event.open("TestFluentdEvent_USR1")
       event.set
       event.close
+      sleep 1.0 # Wait for dumping
     ensure
       server.stop_windows_event_thread
     end