diff --git a/CHANGELOG.txt b/CHANGELOG.txt
index 903a24278f98465dc7499565cc001da4c670846b..10980a1e9377f6e7679ac84d3630cc2d76584daa 100644
--- a/CHANGELOG.txt
+++ b/CHANGELOG.txt
@@ -1,6 +1,8 @@
 
 Drupal 7.17, xxxx-xx-xx (development version)
 -----------------------
+- Fixed a bug which prevented required form elements without a title from being
+  given an "error" class when the form fails validation.
 - Prevented duplicate HTML IDs from appearing when two forms are displayed on
   the same page and one of them is submitted with invalid data (minor markup
   change).
diff --git a/includes/form.inc b/includes/form.inc
index fa49839e4570397e7c576b734fc4778c6d6563f1..aa90eca691ad4a23f76d574641311cb448b5aa5b 100644
--- a/includes/form.inc
+++ b/includes/form.inc
@@ -4199,7 +4199,7 @@ function _form_set_class(&$element, $class = array()) {
   if (!empty($element['#required'])) {
     $element['#attributes']['class'][] = 'required';
   }
-  if (isset($element['#parents']) && form_get_error($element)) {
+  if (isset($element['#parents']) && form_get_error($element) !== NULL) {
     $element['#attributes']['class'][] = 'error';
   }
 }
diff --git a/modules/simpletest/tests/form.test b/modules/simpletest/tests/form.test
index 620621a69d349ef61e670e925dbce141288464cf..7eac198ad2c942e71929b9a4d044b81984cc525d 100644
--- a/modules/simpletest/tests/form.test
+++ b/modules/simpletest/tests/form.test
@@ -189,6 +189,38 @@ class FormsTestCase extends DrupalWebTestCase {
     $this->assertRaw("The form_test_validate_required_form form was submitted successfully.", 'Validation form submitted successfully.');
   }
 
+  /**
+   * Tests validation for required textfield element without title.
+   *
+   * Submits a test form containing a textfield form elements without title.
+   * The form is submitted twice, first without value for the required field
+   * and then with value. Each submission is checked for relevant error
+   * messages.
+   *
+   * @see form_test_validate_required_form_no_title()
+   */
+  function testRequiredTextfieldNoTitle() {
+    $form = $form_state = array();
+    $form = form_test_validate_required_form_no_title($form, $form_state);
+
+    // Attempt to submit the form with no required field set.
+    $edit = array();
+    $this->drupalPost('form-test/validate-required-no-title', $edit, 'Submit');
+    $this->assertNoRaw("The form_test_validate_required_form_no_title form was submitted successfully.", 'Validation form submitted successfully.');
+
+    // Check the page for the error class on the textfield.
+    $this->assertFieldByXPath('//input[contains(@class, "error")]', FALSE, 'Error input form element class found.');
+
+    // Submit again with required fields set and verify that there are no
+    // error messages.
+    $edit = array(
+      'textfield' => $this->randomString(),
+    );
+    $this->drupalPost(NULL, $edit, 'Submit');
+    $this->assertNoFieldByXpath('//input[contains(@class, "error")]', FALSE, 'No error input form element class found.');
+    $this->assertRaw("The form_test_validate_required_form_no_title form was submitted successfully.", 'Validation form submitted successfully.');
+  }
+
   /**
    * Test default value handling for checkboxes.
    *
diff --git a/modules/simpletest/tests/form_test.module b/modules/simpletest/tests/form_test.module
index 6af18c6aff4c403961994c6ce79071b85c4aa88a..b4d2f54990048b5612611de77ef015a51880d856 100644
--- a/modules/simpletest/tests/form_test.module
+++ b/modules/simpletest/tests/form_test.module
@@ -30,6 +30,13 @@ function form_test_menu() {
     'access callback' => TRUE,
     'type' => MENU_CALLBACK,
   );
+  $items['form-test/validate-required-no-title'] = array(
+    'title' => 'Form #required validation without #title',
+    'page callback' => 'drupal_get_form',
+    'page arguments' => array('form_test_validate_required_form_no_title'),
+    'access callback' => TRUE,
+    'type' => MENU_CALLBACK,
+  );
   $items['form-test/limit-validation-errors'] = array(
     'title' => 'Form validation with some error suppression',
     'page callback' => 'drupal_get_form',
@@ -412,6 +419,26 @@ function form_test_validate_required_form_submit($form, &$form_state) {
   drupal_set_message('The form_test_validate_required_form form was submitted successfully.');
 }
 
+/**
+ * Form constructor to test the #required property without #title.
+ */
+function form_test_validate_required_form_no_title($form, &$form_state) {
+  $form['textfield'] = array(
+    '#type' => 'textfield',
+    '#required' => TRUE,
+  );
+  $form['actions'] = array('#type' => 'actions');
+  $form['actions']['submit'] = array('#type' => 'submit', '#value' => 'Submit');
+  return $form;
+}
+
+/**
+ * Form submission handler for form_test_validate_required_form_no_title().
+ */
+function form_test_validate_required_form_no_title_submit($form, &$form_state) {
+  drupal_set_message('The form_test_validate_required_form_no_title form was submitted successfully.');
+}
+
 /**
  * Builds a simple form with a button triggering partial validation.
  */