diff --git a/mail_imap_ssl.t b/mail_imap_ssl.t
index cce45f1..4ba3bbe 100644
--- a/mail_imap_ssl.t
+++ b/mail_imap_ssl.t
@@ -207,7 +207,7 @@
 );
 $s->ok('trusted cert');
 $s->send('1 AUTHENTICATE PLAIN ' . $cred->("s5"));
-$s->read();
+undef $s;
 
 # test auth_http request header fields with access_log