charset issue in application/rss+xml pages

Hi there,
There is a bug in caching unicode pages in RSS!
Boost save cache files in non unicode format when saving views RSS pages. so non english characters shows like "آیا به همسرتان حسادت"
I searched between headers before and after turning on boost and found Boost deletes charset in content-type header and sets "application/rss+xml;" instead of "application/rss+xml; charset=utf-8"!
so how can we solve this?