diff --git a/lib/Cake/bootstrap.php b/lib/Cake/bootstrap.php
index f4469ccbe..228145b34 100644
--- a/lib/Cake/bootstrap.php
+++ b/lib/Cake/bootstrap.php
@@ -174,6 +174,9 @@ if (function_exists('mb_internal_encoding')) {
 	if (!empty($encoding)) {
 		mb_internal_encoding($encoding);
 	}
+	if (!empty($encoding) && function_exists('mb_regex_encoding')) {
+		mb_regex_encoding($encoding);
+	}
 }
 
 if (!function_exists('mb_stripos')) {