diff --git modules/block/block.module modules/block/block.module
index ae4889e..d19a27f 100644
--- modules/block/block.module
+++ modules/block/block.module
@@ -241,9 +241,28 @@ function block_block_save($delta = 0, $edit = array()) {
  * Generates the administrator-defined blocks for display.
  */
 function block_block_view($delta = '') {
-  $block = db_query('SELECT body, format FROM {block_custom} WHERE bid = :bid', array(':bid' => $delta))->fetchObject();
-  $data['subject'] = NULL;
-  $data['content'] = check_markup($block->body, $block->format, '', TRUE);
+  // Retrieve the default title and the content of the custom block.
+  $query = db_select('block_custom', 'bc');
+  $query->join('block', 'b', 'bc.bid = b.delta');
+  $block = $query
+    ->addTag('translatable')
+    ->addTag('block_load')
+    ->fields('b', array('title'))
+    ->fields('bc', array('body', 'format'))
+    ->condition('bc.bid', $delta)
+    ->range(0, 1)
+    ->execute()
+    ->fetchObject();
+
+  $data = array(
+    // Only module-generated block titles are allowed to output any HTML markup.
+    // Custom block titles are always user input and therefore always escaped.
+    // @see _block_render_blocks()
+    'subject' => $block->title == '<none>' ? '' : check_plain($block->title),
+    'content' => array(
+      '#markup' => check_markup($block->body, $block->format, '', TRUE),
+    ),
+  );
   return $data;
 }
 
diff --git modules/block/block.test modules/block/block.test
index 5a184d0..2bbc83d 100644
--- modules/block/block.test
+++ modules/block/block.test
@@ -81,8 +81,8 @@ class BlockTestCase extends DrupalWebTestCase {
     // Check that block_block_view() returns the correct title and content.
     $data = block_block_view($bid);
     $format = db_query("SELECT format FROM {block_custom} WHERE bid = :bid", array(':bid' => $bid))->fetchField();
-    $this->assertTrue(array_key_exists('subject', $data) && empty($data['subject']), t('block_block_view() provides an empty block subject, since custom blocks do not have default titles.'));
-    $this->assertEqual(check_markup($custom_block['body[value]'], $format), $data['content'], t('block_block_view() provides correct block content.'));
+    $this->assertEqual($custom_block['title'], $data['subject'], t('block_block_view() provides correct block title.'));
+    $this->assertEqual(check_markup($custom_block['body[value]'], $format), $data['content']['#markup'], t('block_block_view() provides correct block content.'));
 
     // Check if the block can be moved to all availble regions.
     $custom_block['module'] = 'block';