The solution is to use a custom filetype.vim and 'scripts.vim'. In filetype.vim add: au BufNewFile,BufRead *.h call FTCheck_inform() and after augroup END add " function to detect inform code (any extension) fun! FTCheck_inform() if getline(1) =~ "^!" setfiletype inform elseif getline(2) =~ "^!" setfiletype inform else let s:colnum = col('.') let s:linenum = line('.') call cursor(500, 1) if search('\[\(\s*\I\i*\)*\s*;', 'bW') > 0 setfiletype inform endif call cursor(s:linenum, s:colnum) endif endfun For files with no extension, create a '$HOME/.vim/scripts.vim': See also the site