to this: " 'nomodifiable' disallows changes to 'fileformat' and 'fileencoding' so remove those entries in the else clause function! Noma_workaround() if exists("modifiable") set tw=77 ai nocindent fileencoding=iso-8859-1 else set tw=77 ai nocindent endif endfunction au BufNewFile,BufRead mutt*,*.txt,*/.followup call Noma_workaround() In short this just mean that I call the Noma_workaround() function to determine if I can set the fileencoding or if that will give an error. In that case I jsut set the other options.