Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 6100)
+++ wp-includes/formatting.php	(working copy)
@@ -44,10 +44,18 @@
   	return $output;
 }
 
-function clean_pre($text) {
+// Accepts matches array from preg_replace_callback in wpautop()
+// or a string
+function clean_pre($matches) {
+	if ( is_array($matches) )
+		$text = $matches[1] . $matches[2] . "</pre>";
+	else
+		$text = $matches;
+
 	$text = str_replace('<br />', '', $text);
 	$text = str_replace('<p>', "\n", $text);
 	$text = str_replace('</p>', '', $text);
+
 	return $text;
 }
 
@@ -78,7 +86,7 @@
 	$pee = preg_replace('!(</?' . $allblocks . '[^>]*>)\s*<br />!', "$1", $pee);
 	$pee = preg_replace('!<br />(\s*</?(?:p|li|div|dl|dd|dt|th|pre|td|ul|ol)[^>]*>)!', '$1', $pee);
 	if (strpos($pee, '<pre') !== false)
-		$pee = preg_replace('!(<pre.*?>)(.*?)</pre>!ise', " stripslashes('$1') .  stripslashes(clean_pre('$2'))  . '</pre>' ", $pee);
+		$pee = preg_replace_callback('!(<pre.*?>)(.*?)</pre>!is', 'clean_pre', $pee );
 	$pee = preg_replace( "|\n</p>$|", '</p>', $pee );
 
 	return $pee;