diff --git a/ftplugin/ats.vim b/ftplugin/ats.vim
new file mode 100644
index 0000000..8fd73d7
--- /dev/null
+++ b/ftplugin/ats.vim
@@ -0,0 +1,28 @@
+if exists('b:ats_ftplugin')
+	finish
+endif
+let b:ats_ftplugin = 1
+
+if !exists('g:ats_autoformat')
+    let g:ats_autoformat = 0
+endif
+
+set smarttab
+au BufNewFile,BufRead *.*ats
+    \ set shiftwidth=2
+
+setlocal commentstring=(*\ %s\ *)
+
+function! AtsFormat()
+    exec 'normal! gg'
+    exec 'silent !atsfmt -i ' . expand('%')
+    exec 'e'
+endfunction
+
+if g:ats_autoformat == 1
+    augroup ats
+            autocmd BufWritePost *.ats,*.dats,*.sats,*.cats call AtsFormat()
+    augroup END
+endif
+
+command Format call AtsFormat()
diff --git a/syntax/ats.vim b/syntax/ats.vim
index 2a7e507..b32ae69 100644
--- a/syntax/ats.vim
+++ b/syntax/ats.vim
@@ -68,7 +68,7 @@ endif
 
 " keyword highlighting
 syn keyword atsKeyword prefix postfix infix infixl infixr op nonfix
-syn keyword atsKeyword staload stadef sta dynload
+syn keyword atsKeyword staload stadef sta dynload stacst
 syn keyword atsCond if then else case sif
 syn keyword atsRepeat while
 syn keyword atsException exception raise try