diff --git a/ext/mbstring/tests/zend_multibyte-02.phpt b/ext/mbstring/tests/zend_multibyte-02.phpt
index 84eae89d9e0..ebc10b48beb 100644
--- a/ext/mbstring/tests/zend_multibyte-02.phpt
+++ b/ext/mbstring/tests/zend_multibyte-02.phpt
@@ -1,6 +1,7 @@
 --TEST--
 zend multibyte (2)
---SKIPIF--
+--XFAIL--
+https://bugs.php.net/bug.php?id=66582
 --INI--
 zend.multibyte=On
 zend.script_encoding=UTF-8
diff --git a/ext/mbstring/tests/zend_multibyte-06.phpt b/ext/mbstring/tests/zend_multibyte-06.phpt
index 11e263f0b68..e0b4ead545b 100644
--- a/ext/mbstring/tests/zend_multibyte-06.phpt
+++ b/ext/mbstring/tests/zend_multibyte-06.phpt
@@ -1,6 +1,7 @@
 --TEST--
 zend multibyte (6)
---SKIPIF--
+--XFAIL--
+https://bugs.php.net/bug.php?id=66582
 --INI--
 zend.multibyte=On
 zend.script_encoding=EUC-JP