diff --git a/metatags_quick.module b/metatags_quick.module
index 980de06..39d38fc 100644
--- a/metatags_quick.module
+++ b/metatags_quick.module
@@ -120,7 +120,7 @@ function metatags_quick_entity_load($entities, $type) {
  */
 function metatags_quick_field_validate($obj_type, $object, $field, $instance, $langcode, $items, &$errors) {
   foreach ($items as $delta => $item) {
-    if (!empty($item['metatags_quick']) && strlen($item['metatags_quick']) > 255) {
+    if (!empty($item['metatags_quick']) && mb_strlen($item['metatags_quick'], 'UTF-8') > 255) {
       $error = t('%name: the value may not be longer than %max characters.', array('%name' => $instance['label'], '%max' => 255));
       $errors[$field['field_name']][$langcode][$delta][] = array(
         'error' => $error,