diff --git a/include/class.validator.php b/include/class.validator.php
index 28bf61c2b90f917c97b31a2b6bf049b2b7668299..127cfb93b485eb1c1801ee727112534c86ee6736 100644
--- a/include/class.validator.php
+++ b/include/class.validator.php
@@ -141,8 +141,8 @@ class Validator {
     /*** Functions below can be called directly without class instance.
          Validator::func(var..);  (nolint) ***/
     function is_email($email, $list=false) {
-        require_once 'Mail/RFC822.php';
-        require_once 'PEAR.php';
+        require_once PEAR_DIR . 'Mail/RFC822.php';
+        require_once PEAR_DIR . 'PEAR.php';
         if (!($mails = Mail_RFC822::parseAddressList($email)) || PEAR::isError($mails))
             return false;