diff --git a/plugin/sensible.vim b/plugin/sensible.vim
index a4900fa..d4ba37d 100644
--- a/plugin/sensible.vim
+++ b/plugin/sensible.vim
@@ -141,6 +141,11 @@ if exists(":DiffOrig") != 2
         \ | diffthis | wincmd p | diffthis
 endif
 
+" Correctly highlight $() and other modern affordances in filetype=sh.
+if !exists('g:is_posix') && !exists('g:is_bash') && !exists('g:is_kornshell') && !exists('g:is_dash')
+  let g:is_posix = 1
+endif
+
 " Load matchit.vim, but only if the user hasn't installed a newer version.
 if !exists('g:loaded_matchit') && findfile('plugin/matchit.vim', &rtp) ==# ''
   runtime! macros/matchit.vim