diff --git a/mod/book/edit_form.php b/mod/book/edit_form.php
index 9a8cbf4d776..e681e563096 100644
--- a/mod/book/edit_form.php
+++ b/mod/book/edit_form.php
@@ -55,9 +55,11 @@ class book_chapter_edit_form extends moodleform {
             );
         }
 
-        $mform->addElement('text', 'title', get_string('chaptertitle', 'mod_book'), array('size'=>'30'));
+        $mform->addElement('text', 'title', get_string('chaptertitle', 'mod_book'),
+            ['size' => '30', 'maxlength' => '255']);
         $mform->setType('title', PARAM_RAW);
         $mform->addRule('title', null, 'required', null, 'client');
+        $mform->addRule('title', get_string('maximumchars', '', 255), 'maxlength', 255, 'client');
 
         $mform->addElement('advcheckbox', 'subchapter', get_string('subchapter', 'mod_book'), $disabledmsg);