Index: xml_format.inc
===================================================================
--- xml_format.inc	(revision 1825)
+++ xml_format.inc	(working copy)
@@ -57,7 +57,7 @@
       }
       if ($synonyms) {
         $output .= "<synonyms>";
-        $output .= implode("\n", $synonyms);
+        $output .= implode("\n", array_map('check_plain', $synonyms));
         $output .= "</synonyms>";
       }
       $output .= "</term>";