diff --git a/core/modules/system/tests/modules/form_test/form_test.module b/core/modules/system/tests/modules/form_test/form_test.module
index 03b7cb8..8cf4813 100644
--- a/core/modules/system/tests/modules/form_test/form_test.module
+++ b/core/modules/system/tests/modules/form_test/form_test.module
@@ -437,6 +437,13 @@ function form_test_validate_required_form($form, &$form_state) {
     '#required' => TRUE,
     '#required_error' => t('Please enter a name.'),
   );
+  $form['textfield_david'] = array(
+    '#type' => 'textfield',
+    '#title' => 'David Name',
+    '#required' => TRUE,
+    '#required_error' => t('Please enter a David name.'),
+    '#element_validate' => array('form_test_validate_required_form_element_validate_david'),
+  );
   $form['checkboxes'] = array(
     '#type' => 'checkboxes',
     '#title' => 'Checkboxes',
@@ -484,6 +491,17 @@ function form_test_validate_required_form_element_validate($element, &$form_stat
     form_error($element, $element['#form_test_required_error']);
   }
 }
+/**
+ * Form element validation handler for 'David Name' field.
+ *
+ * @see form_test_validate_required_form().
+ */
+function form_test_validate_required_form_element_validate_david($element, &$form_state) {
+  // Custom validation that assumes the form passed non-empty validation.
+  if ($element['#value'] != 'David') {
+    form_error($element, t('People with the name of %name are not allowed to submit this form.', array('%name' => $element['#value'])));
+  }
+}
 
 /**
  * Form submission handler for form_test_validate_required_form().