--- /dev/null
+--TEST--
+Bug #20226 Mail_mimePart::encodeHeader() and ISO-2022-JP encoding
+--SKIPIF--
+--FILE--
+<?php
+include("Mail/mimePart.php");
+
+$subject = base64_decode("GyRCJT8lJCVIJWsbKEI=");
+$mime = new Mail_mimePart();
+
+echo $mime->encodeHeader('subject', $subject, 'ISO-2022-JP', 'base64');
+?>
+--EXPECT--
+=?ISO-2022-JP?B?GyRCJT8lJCVIJWsbKEI=?=