diff --git a/system/libraries/Email.php b/system/libraries/Email.php
index 71740ee..a53e7e7 100644
--- a/system/libraries/Email.php
+++ b/system/libraries/Email.php
@@ -1856,7 +1856,7 @@
 		if (function_exists('idn_to_ascii') && strpos($email, '@'))
 		{
 			list($account, $domain) = explode('@', $email, 2);
-			$domain = is_php('5.4')
+			$domain = defined('INTL_IDNA_VARIANT_UTS46')
 				? idn_to_ascii($domain, 0, INTL_IDNA_VARIANT_UTS46)
 				: idn_to_ascii($domain);
 			$email = $account.'@'.$domain;