I have been using a macro to save files in the xls format but I now need to update that macro to save the files as the xlsx format. Below is the current vba I'm using.
What do I change to get it to save in the xlsx format?

Dim FName As String
FName = Application.GetSaveAsFilename(FileFilter:="Excel 97-2003 Workbook (*.xls),*.xls")
ActiveWorkbook.SaveAs Filename:=FName, FileFormat:=xlExcel8