Index: formatting.php
===================================================================
--- formatting.php      (revision 21516)
+++ formatting.php      (working copy)
@@ -216,7 +216,8 @@
        if (strpos($pee, '<pre') !== false)
                $pee = preg_replace_callback('!(<pre[^>]*>)(.*?)</pre>!is', 'clean_pre', $pee );
        $pee = preg_replace( "|\n</p>$|", '</p>', $pee );
-       $pee = preg_replace('/<p>\s*?(' . get_shortcode_regex() . ')\s*<\/p>/s', '$1', $pee); // don't auto-p wrap shortcodes that stand alone
+       if ( function_exists( 'get_shortcode_regex' ) )
+               $pee = preg_replace('/<p>\s*?(' . get_shortcode_regex() . ')\s*<\/p>/s', '$1', $pee); // don't auto-p wrap shortcodes that stand alone

        return $pee;
 }