--- diff/diff.theme.inc	2010-08-12 12:34:08.000000000 -0400
+++ diff/diff.theme.inc	2010-09-13 11:55:33.992000819 -0400
@@ -16,6 +16,7 @@ function theme_diff_node_revisions($form
   // Overview table:
   $header = array(
     t('Revision'),
+    array('data' =>  drupal_render($form['incmarkup'])),
     array('data' => drupal_render($form['submit']), 'colspan' => 2),
     array('data' => t('Operations'), 'colspan' => 2)
   );