Index: comment.php
===================================================================
--- comment.php	(revision 12121)
+++ comment.php	(working copy)
@@ -768,7 +768,7 @@
 
 	$where = '';
 	if ( $post_id > 0 )
-		$where = $wpdb->prepare( "comment_post_ID = %d AND ", $post_id );
+		$where = $wpdb->prepare( "WHERE comment_post_ID = %d ", $post_id );
 
 	$count = $wpdb->get_results( "SELECT comment_approved, COUNT( * ) AS num_comments FROM {$wpdb->comments} {$where} GROUP BY comment_approved", ARRAY_A );