docx and xlsx have a zip/application mimetype
diff --git a/application/config/mimes.php b/application/config/mimes.php
index f00e5b6..100f7d4 100644
--- a/application/config/mimes.php
+++ b/application/config/mimes.php
@@ -93,8 +93,8 @@
 				'avi'	=>	'video/x-msvideo',
 				'movie'	=>	'video/x-sgi-movie',
 				'doc'	=>	'application/msword',
-				'docx'	=>	'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
-				'xlsx'	=>	'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+				'docx'	=>	array('application/vnd.openxmlformats-officedocument.wordprocessingml.document', 'application/zip'),
+				'xlsx'	=>	array('application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 'application/zip'),
 				'word'	=>	array('application/msword', 'application/octet-stream'),
 				'xl'	=>	'application/excel',
 				'eml'	=>	'message/rfc822',