Index: modules/filter/filter.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/filter/filter.module,v
retrieving revision 1.160.2.13
diff -u -p -r1.160.2.13 filter.module
--- modules/filter/filter.module	28 Jan 2009 22:45:42 -0000	1.160.2.13
+++ modules/filter/filter.module	24 May 2009 23:20:39 -0000
@@ -1187,7 +1187,7 @@ function _filter_url_trim($text, $length
  */
 function _filter_autop($text) {
   // All block level tags
-  $block = '(?:table|thead|tfoot|caption|colgroup|tbody|tr|td|th|div|dl|dd|dt|ul|ol|li|pre|select|form|blockquote|address|p|h[1-6])';
+  $block = '(?:table|thead|tfoot|caption|colgroup|tbody|tr|td|th|div|dl|dd|dt|ul|ol|li|pre|select|form|blockquote|address|p|h[1-6]|hr)';
 
   // Split at <pre>, <script>, <style> and </pre>, </script>, </style> tags.
   // We don't apply any processing to the contents of these tags to avoid messing