Index: branches/RC/core/kernel/utility/formatters/upload_formatter.php
===================================================================
diff -u -r9652 -r10098
--- branches/RC/core/kernel/utility/formatters/upload_formatter.php	(.../upload_formatter.php)	(revision 9652)
+++ branches/RC/core/kernel/utility/formatters/upload_formatter.php	(.../upload_formatter.php)	(revision 10098)
@@ -266,7 +266,7 @@
 	{
 		$parts = pathinfo($name);
 		$ext = '.'.$parts['extension'];
-		$filename = substr($parts['basename'], 0, -strlen($ext));
+		$filename = mb_substr($parts['basename'], 0, -mb_strlen($ext));
 		$new_name = $filename.$ext;
 		while ( file_exists($path.'/'.$new_name) || in_array(rtrim($path, '/').'/'.$new_name, $forbidden_names) )
 		{