Index: wp-includes/media.php
===================================================================
--- wp-includes/media.php	(revision 17287)
+++ wp-includes/media.php	(working copy)
@@ -862,6 +862,10 @@
 				<{$captiontag} class='wp-caption-text gallery-caption'>
 				" . wptexturize($attachment->post_excerpt) . "
 				</{$captiontag}>";
+		} elseif ( 'dd' == $captiontag ) {
+			$output .= "
+				<{$captiontag} class='gallery-caption'>
+				</{$captiontag}>";
 		}
 		$output .= "</{$itemtag}>";
 		if ( $columns > 0 && ++$i % $columns == 0 )