diff --git a/modules/comment/comment.module b/modules/comment/comment.module
index d04755db261..18e0e67d09a 100644
--- a/modules/comment/comment.module
+++ b/modules/comment/comment.module
@@ -423,19 +423,35 @@ function comment_new_page_count($num_comments, $new_replies, $node) {
     $pageno =  $count / $comments_per_page;
   }
   else {
-    // Threaded comments.
-    // Find the first thread with a new comment.
-    $result = db_query_range('SELECT thread FROM (SELECT thread
-      FROM {comment}
-      WHERE nid = :nid
-        AND status = 0
-      ORDER BY changed DESC) AS thread
-      ORDER BY SUBSTRING(thread, 1, (LENGTH(thread) - 1))', 0, $new_replies, array(':nid' => $node->nid))->fetchField();
-    $thread = substr($result, 0, -1);
-    $count = db_query('SELECT COUNT(*) FROM {comment} WHERE nid = :nid AND status = 0 AND SUBSTRING(thread, 1, (LENGTH(thread) - 1)) < :thread', array(
+    // Threaded comments: we build a query with a subquery to find the first
+    // thread with a new comment.
+
+    // 1. Find all the threads with a new comment.
+    $unread_threads_query = db_select('comment')
+      ->fields('comment', array('thread'))
+      ->condition('nid', $node->nid)
+      ->condition('status', COMMENT_PUBLISHED)
+      ->orderBy('changed', 'DESC')
+      ->range(0, $new_replies);
+
+    // 2. Find the first thread.
+    $first_thread = db_select($unread_threads_query, 'thread')
+      ->fields('thread', array('thread'))
+      ->orderBy('SUBSTRING(thread, 1, (LENGTH(thread) - 1))')
+      ->range(0, 1)
+      ->execute()
+      ->fetchField();
+
+    // Remove the final '/'.
+    $first_thread = substr($first_thread, 0, -1);
+
+    // Find the number of the first comment of the first unread thread.
+    $count = db_query('SELECT COUNT(*) FROM {comment} WHERE nid = :nid AND status = :status AND SUBSTRING(thread, 1, (LENGTH(thread) - 1)) < :thread', array(
+      ':status' => COMMENT_PUBLISHED,
       ':nid' => $node->nid,
-      ':thread' => $thread,
+      ':thread' => $first_thread,
     ))->fetchField();
+
     $pageno =  $count / $comments_per_page;
   }
 
diff --git a/modules/comment/comment.test b/modules/comment/comment.test
index 60c4b3142e3..6fd91907f85 100644
--- a/modules/comment/comment.test
+++ b/modules/comment/comment.test
@@ -763,6 +763,85 @@ class CommentPagerTest extends CommentHelperCase {
 
     return $this->assertIdentical($expected_cids, $result_order, t('Comment order: expected @expected, returned @returned.', array('@expected' => implode(',', $expected_cids), '@returned' => implode(',', $result_order))));
   }
+
+  /**
+   * Test comment_new_page_count().
+   */
+  function testCommentNewPageIndicator() {
+    $this->drupalLogin($this->admin_user);
+
+    // Set comment variables.
+    $this->setCommentForm(TRUE);
+    $this->setCommentSubject(TRUE);
+    $this->setCommentPreview(FALSE);
+
+    // Set comments to one per page so that we are able to test paging without
+    // needing to insert large numbers of comments.
+    $this->setCommentsPerPage(1);
+
+    // Create a node and three comments.
+    $node = $this->drupalCreateNode(array('type' => 'article', 'promote' => 1));
+    $comments = array();
+    $comments[] = $this->postComment($node, $this->randomName(), $this->randomName(), TRUE);
+    $comments[] = $this->postComment($node, $this->randomName(), $this->randomName(), TRUE);
+    $comments[] = $this->postComment($node, $this->randomName(), $this->randomName(), TRUE);
+
+    // Post a reply to the second comment.
+    $this->drupalGet('comment/reply/' . $node->nid . '/' . $comments[1]->id);
+    $comments[] = $this->postComment(NULL, $this->randomName(), $this->randomName(), TRUE);
+
+    // Post a reply to the first comment.
+    $this->drupalGet('comment/reply/' . $node->nid . '/' . $comments[0]->id);
+    $comments[] = $this->postComment(NULL, $this->randomName(), $this->randomName(), TRUE);
+
+    // Post a reply to the last comment.
+    $this->drupalGet('comment/reply/' . $node->nid . '/' . $comments[2]->id);
+    $comments[] = $this->postComment(NULL, $this->randomName(), $this->randomName(), TRUE);
+
+    // At this point, the comment tree is:
+    // - 0
+    //   - 4
+    // - 1
+    //   - 3
+    // - 2
+    //   - 5
+
+    $this->setCommentSettings('comment_default_mode', COMMENT_MODE_FLAT, t('Comment paging changed.'));
+
+    $expected_pages = array(
+      1 => 5, // Page of comment 5
+      2 => 4, // Page of comment 4
+      3 => 3, // Page of comment 3
+      4 => 2, // Page of comment 2
+      5 => 1, // Page of comment 1
+      6 => 0, // Page of comment 0
+    );
+
+    $node = node_load($node->nid);
+    foreach ($expected_pages as $new_replies => $expected_page) {
+      $returned = comment_new_page_count($node->comment_count, $new_replies, $node);
+      $returned_page = is_array($returned) ? $returned['page'] : 0;
+      $this->assertIdentical($expected_page, $returned_page, t('Flat mode, @new replies: expected page @expected, returned page @returned.', array('@new' => $new_replies, '@expected' => $expected_page, '@returned' => $returned_page)));
+    }
+
+    $this->setCommentSettings('comment_default_mode', COMMENT_MODE_THREADED, t('Switched to threaded mode.'));
+
+    $expected_pages = array(
+      1 => 5, // Page of comment 5
+      2 => 1, // Page of comment 4
+      3 => 1, // Page of comment 4
+      4 => 1, // Page of comment 4
+      5 => 1, // Page of comment 4
+      6 => 0, // Page of comment 0
+    );
+
+    $node = node_load($node->nid);
+    foreach ($expected_pages as $new_replies => $expected_page) {
+      $returned = comment_new_page_count($node->comment_count, $new_replies, $node);
+      $returned_page = is_array($returned) ? $returned['page'] : 0;
+      $this->assertEqual($expected_page, $returned_page, t('Threaded mode, @new replies: expected page @expected, returned page @returned.', array('@new' => $new_replies, '@expected' => $expected_page, '@returned' => $returned_page)));
+    }
+  }
 }
 
 class CommentApprovalTest extends CommentHelperCase {