diff --git a/test/net/imap/test_imap.rb b/test/net/imap/test_imap.rb
index ecec2a5d5e..0f171e6a1d 100644
--- a/test/net/imap/test_imap.rb
+++ b/test/net/imap/test_imap.rb
@@ -494,7 +494,6 @@ class IMAPTest < Test::Unit::TestCase
       end
     ensure
       ssl_server.close
-      ths.kill
       ths.join
     end
   end