Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 31834)
+++ src/wp-includes/formatting.php	(working copy)
@@ -1069,7 +1069,7 @@
  */
 function sanitize_file_name( $filename ) {
 	$filename_raw = $filename;
-	$special_chars = array("?", "[", "]", "/", "\\", "=", "<", ">", ":", ";", ",", "'", "\"", "&", "$", "#", "*", "(", ")", "|", "~", "`", "!", "{", "}", chr(0));
+	$special_chars = array("?", "[", "]", "/", "\\", "=", "<", ">", ":", ";", ",", "'", "\"", "&", "$", "#", "*", "(", ")", "|", "~", "`", "!", "{", "}", "%", "+", chr(0));
 	/**
 	 * Filter the list of characters to remove from a filename.
 	 *