how do i use UPX safely?

I am trying to reduce my application size with upx using --lzma compression method.

But, whenever I use upx and scan my application after compress, its shows that this application has virus. This is the virus result that comes up

Gen:Adware.Heur.RmTfWDj6fzli

If I scan the application before using upx, application is totally clean and no virus detected.

How do I avoid this issue?

I am using upx 391 from here http://upx.sourceforge.net/

You can't avoid this issue.

The problem is that malware authors often use UPX and other packers to reduce size and try to conceal content, and therefore all of the virus scanners look for signs of those packers (especially UPX, because it's readily available).

If you don't want UPX to cause your app to be identified as being a virus, stop using UPX.