Index: src/main/java/com/xpn/xwiki/web/DownloadAction.java
===================================================================
--- src/main/java/com/xpn/xwiki/web/DownloadAction.java	(revision 28363)
+++ src/main/java/com/xpn/xwiki/web/DownloadAction.java	(working copy)
@@ -76,6 +76,7 @@
         // Choose the right content type
         String mimetype = attachment.getMimeType(context);
         response.setContentType(mimetype);
+        response.setCharacterEncoding("");
 
         String ofilename =
             Util.encodeURI(attachment.getFilename(), context).replaceAll("\\+", " ");