diff --git a/after/ftplugin/haskell/ghcmod.vim b/after/ftplugin/haskell/ghcmod.vim
index 5492baa..f453713 100644
--- a/after/ftplugin/haskell/ghcmod.vim
+++ b/after/ftplugin/haskell/ghcmod.vim
@@ -59,6 +59,7 @@ command! -buffer -nargs=0 -bang GhcModCheckAsync call ghcmod#command#async_make(
 command! -buffer -nargs=0 -bang GhcModLintAsync call ghcmod#command#async_make('lint', <bang>0)
 command! -buffer -nargs=0 -bang GhcModCheckAndLintAsync call ghcmod#command#check_and_lint_async(<bang>0)
 command! -buffer -nargs=0 -bang GhcModExpand call ghcmod#command#expand(<bang>0)
+command! -buffer -nargs=0 -bang GhcModKillModi call ghcmod#command#kill_modi(<bang>0)
 let b:undo_ftplugin .= join(map([
       \ 'GhcModType',
       \ 'GhcModTypeInsert',
@@ -72,7 +73,8 @@ let b:undo_ftplugin .= join(map([
       \ 'GhcModCheckAsync',
       \ 'GhcModLintAsync',
       \ 'GhcModCheckAndLintAsync',
-      \ 'GhcModExpand'
+      \ 'GhcModExpand',
+      \ 'GhcModKillModi'
       \ ], '"delcommand " . v:val'), ' | ')
 let b:undo_ftplugin .= ' | unlet b:did_ftplugin_ghcmod'
 
diff --git a/autoload/ghcmod.vim b/autoload/ghcmod.vim
index 145c614..7df3396 100644
--- a/autoload/ghcmod.vim
+++ b/autoload/ghcmod.vim
@@ -1,3 +1,9 @@
+if !exists("g:ghcmod_should_use_ghc_modi")
+  let g:ghcmod_should_use_ghc_modi = 1
+endif
+
+let s:use_modi = g:ghcmod_should_use_ghc_modi
+
 function! ghcmod#highlight_group() "{{{
   return get(g:, 'ghcmod_type_highlight', 'Search')
 endfunction "}}}
@@ -15,8 +21,8 @@ function! ghcmod#getHaskellIdentifier() "{{{
 endfunction "}}}
 
 function! ghcmod#info(fexp, path, ...) "{{{
-  let l:cmd = ghcmod#build_command(["-b \n", 'info', a:path, a:fexp])
-  let l:output = ghcmod#system(l:cmd)
+  let l:lines = s:command(['info', a:path, a:fexp])
+  let l:output = join(split(l:lines[0], '\\n'), "\n")
   " Remove trailing newlines to prevent empty lines
   let l:output = substitute(l:output, '\n*$', '', '')
   return s:remove_dummy_prefix(l:output)
@@ -24,22 +30,20 @@ endfunction "}}}
 
 function! ghcmod#split(line, col, path, ...) "{{{
   " `ghc-mod split` is available since v5.0.0.
-  let l:cmd = ghcmod#build_command(['split', a:path, a:line, a:col])
-  let l:lines = s:system('split', l:cmd)
+  let l:lines = s:command(['split', a:path, a:line, a:col])
   if empty(l:lines)
     return []
   endif
-  let l:parsed = matchlist(l:lines[0], '\(\d\+\) \(\d\+\) \(\d\+\) \(\d\+\) "\(.*\)"')
+  let l:parsed = matchlist(l:lines[0], '^\(\d\+\) \(\d\+\) \(\d\+\) \(\d\+\) "\([^"]\+\)"$')
   if len(l:parsed) < 5
     return []
   endif
-  return split(l:parsed[5], '\n')
+  return split(l:parsed[5], '\\n')
 endfunction "}}}
 
 function! ghcmod#sig(line, col, path, ...) "{{{
   " `ghc-mod sig` is available since v5.0.0.
-  let l:cmd = ghcmod#build_command(['sig', a:path, a:line, a:col])
-  let l:lines = s:system('sig', l:cmd)
+  let l:lines = s:command(['sig', a:path, a:line, a:col])
   if len(l:lines) < 3
     return []
   endif
@@ -47,11 +51,10 @@ function! ghcmod#sig(line, col, path, ...) "{{{
 endfunction "}}}
 
 function! ghcmod#type(line, col, path, ...) "{{{
-  let l:cmd = ghcmod#build_command(['type', a:path, a:line, a:col])
-  let l:output = ghcmod#system(l:cmd)
+  let l:lines = s:command(['type', a:path, a:line, a:col])
   let l:types = []
-  for l:line in split(l:output, '\n')
-    let l:m = matchlist(l:line, '\(\d\+\) \(\d\+\) \(\d\+\) \(\d\+\) "\([^"]\+\)"')
+  for l:line in l:lines
+    let l:m = matchlist(l:line, '^\(\d\+\) \(\d\+\) \(\d\+\) \(\d\+\) "\([^"]\+\)"$')
     if !empty(l:m)
       call add(l:types, [map(l:m[1 : 4], 'str2nr(v:val, 10)'), l:m[5]])
     endif
@@ -114,7 +117,7 @@ function! ghcmod#parse_make(lines, basedir) "{{{
     else
       let l:qf.type = 'E'
     endif
-    let l:texts = split(l:rest, '\n')
+    let l:texts = split(l:rest, '\\n')
     if len(l:texts) > 0
       let l:qf.text = l:texts[0]
       call add(l:qflist, l:qf)
@@ -135,21 +138,21 @@ function! ghcmod#parse_make(lines, basedir) "{{{
   return l:qflist
 endfunction "}}}
 
-function! s:build_make_command(type, path) "{{{
-  let l:cmd = ghcmod#build_command([a:type])
+function! s:build_make_args(type, path) "{{{
+  let l:args = [a:type]
   if a:type ==# 'lint'
     for l:hopt in get(g:, 'ghcmod_hlint_options', [])
-      call extend(l:cmd, ['-h', l:hopt])
+      call extend(l:args, ['-h', l:hopt])
     endfor
   endif
-  call add(l:cmd, a:path)
-  return l:cmd
+  call add(l:args, a:path)
+  return l:args
 endfunction "}}}
 
 function! ghcmod#make(type, path) "{{{
   try
-    let l:args = s:build_make_command(a:type, a:path)
-    return ghcmod#parse_make(s:system(a:type, l:args), b:ghcmod_basedir)
+    let l:lines = s:command(s:build_make_args(a:type, a:path))
+    return ghcmod#parse_make(l:lines, b:ghcmod_basedir)
   catch
     call ghcmod#util#print_error(printf('%s %s', v:throwpoint, v:exception))
   endtry
@@ -157,7 +160,7 @@ endfunction "}}}
 
 function! ghcmod#async_make(type, path, callback) "{{{
   let l:tmpfile = tempname()
-  let l:args = s:build_make_command(a:type, a:path)
+  let l:args = ghcmod#build_command(s:build_make_args(a:type, a:path))
   let l:proc = s:plineopen3([{'args': l:args,  'fd': { 'stdin': '', 'stdout': l:tmpfile, 'stderr': '' }}])
   let l:obj = {
         \ 'proc': l:proc,
@@ -183,8 +186,7 @@ function! ghcmod#expand(path) "{{{
   let l:dir = fnamemodify(a:path, ':h')
 
   let l:qflist = []
-  let l:cmd = ghcmod#build_command(['expand', "-b '\n'", a:path])
-  for l:line in split(ghcmod#system(l:cmd), '\n')
+  for l:line in s:command(['expand', a:path])
     let l:line = s:remove_dummy_prefix(l:line)
 
     " path:line:col1-col2: message
@@ -245,7 +247,7 @@ function! ghcmod#add_autogen_dir(path, cmd) "{{{
 endfunction "}}}
 
 function! ghcmod#build_command(args) "{{{
-  let l:cmd = ['ghc-mod', '--silent']
+  let l:cmd = ['ghc-mod', '--silent', '-b\\n']
 
   let l:dist_top  = s:find_basedir() . '/dist'
   let l:sandboxes = split(glob(l:dist_top . '/dist-*', 1), '\n')
@@ -279,6 +281,57 @@ function! ghcmod#build_command(args) "{{{
   return l:cmd
 endfunction "}}}
 
+" Cache a handle to the ghc-modi process.
+let s:ghc_modi_procs = {}
+
+function! s:modi_command(args) "{{{
+  let l:basedir = ghcmod#basedir()
+
+  if has_key(s:ghc_modi_procs, l:basedir)
+    let l:ghc_modi_proc = s:ghc_modi_procs[l:basedir]
+  else
+    let l:ghc_modi_prog = ghcmod#build_command(["legacy-interactive"])
+    let l:ghc_modi_proc = s:plineopen3([{'args': l:ghc_modi_prog, 'fd': { 'stdin': '', 'stdout': '', 'stderr': '/dev/null' }}])
+    let s:ghc_modi_procs[l:basedir] = l:ghc_modi_proc
+  endif
+
+  call l:ghc_modi_proc.stdin.write("ascii-escape " . join(map(copy(a:args), '"\2" . v:val . "\3"')) . "\n")
+
+  let l:res = []
+  while 1
+    for l:line in l:ghc_modi_proc.stdout.read_lines()
+      if l:line == "OK"
+        return l:res
+      elseif line =~ "^NG "
+        echoerr "ghc-modi terminated with message: " . join(l:res, "\n")
+        return ''
+      elseif len(line) > 0
+        let l:res += [l:line]
+      endif
+    endfor
+  endwhile
+endfunction "}}}
+
+function! s:command(args) "{{{
+  if s:use_modi
+    return s:modi_command(a:args)
+  else
+    return s:system(a:args[0], ghcmod#build_command(a:args))
+  endif
+endfunction "}}}
+
+function! ghcmod#kill_modi(sig) "{{{
+  let l:basedir = ghcmod#basedir()
+
+  if has_key(s:ghc_modi_procs, l:basedir)
+    let l:ghc_modi_proc = s:ghc_modi_procs[l:basedir]
+    let l:ret = l:ghc_modi_proc.kill(a:sig)
+    call l:ghc_modi_proc.waitpid()
+    unlet s:ghc_modi_procs[l:basedir]
+    return l:ret
+  endif
+endfunction "}}}
+
 function! ghcmod#system(...) "{{{
   let l:dir = getcwd()
   try
@@ -308,7 +361,7 @@ function! s:system(type, args) "{{{
     let [l:cond, l:status] = ghcmod#util#wait(l:proc)
     let l:tries = 1
     while l:cond ==# 'run'
-      if l:tries >= 50
+      if l:tries >= 500
         call l:proc.kill(15)  " SIGTERM
         call l:proc.waitpid()
         throw printf('ghcmod#make: `ghc-mod %s` takes too long time!', a:type)
diff --git a/autoload/ghcmod/command.vim b/autoload/ghcmod/command.vim
index d8541a7..49ac0b9 100644
--- a/autoload/ghcmod/command.vim
+++ b/autoload/ghcmod/command.vim
@@ -257,6 +257,18 @@ function! ghcmod#command#expand(force) "{{{
   call s:open_quickfix()
 endfunction "}}}
 
+function! ghcmod#command#kill_modi(force) "{{{
+  if a:force
+    let l:sig = g:vimproc#SIGKILL
+  else
+    let l:sig = g:vimproc#SIGINT
+  endif
+  let l:ret = ghcmod#kill_modi(l:sig)
+  if l:ret
+    echoerr vimproc#get_last_errmsg()
+  endif
+endfunction "}}}
+
 function! s:open_quickfix() "{{{
   let l:func = get(g:, 'ghcmod_open_quickfix_function', '')
   if empty(l:func)
diff --git a/test.sh b/test.sh
index d409fa3..1fd7112 100755
--- a/test.sh
+++ b/test.sh
@@ -2,21 +2,39 @@
 
 shopt -s nullglob
 
+run_tests() {
+    for f in $1
+    do
+      testname=${f#test/test_}
+      testname=${testname%.vim}
+      echo "Running $testname"
+      rm -f verbose.log
+      if vim -e -N -u NONE $2 -S test/before.vim -S "$f" < /dev/null; then
+        cat stdout.log
+      else
+        retval=$[retval + 1]
+        cat stdout.log
+        cat verbose.log
+        echo
+      fi
+    done
+}
+
 retval=0
-for f in test/test_*.vim
-do
-  testname=${f#test/test_}
-  testname=${testname%.vim}
-  echo "Running $testname"
-  rm -f verbose.log
-  if vim -e -N -u NONE -S test/before.vim -S "$f" < /dev/null; then
-    cat stdout.log
-  else
-    retval=$[retval + 1]
-    cat stdout.log
-    cat verbose.log
-    echo
-  fi
-done
+
+modonly_tests=(test/test_{expand,check,info,lint,split,type,command_check,command_sig_codegen,command_split,command_type}.vim)
+
+run_tests "test/test_*.vim"
+
+# we cannot programmatically set this in our test case vimscripts as the
+# variable is fixed once the script is loaded
+echo "Setting ghcmod_should_use_ghc_modi=0"
+
+TMPFILE=`mktemp /tmp/test.XXXXXX` || exit 1
+echo "let g:ghcmod_should_use_ghc_modi=0" >> $TMPFILE
+
+run_tests "${modonly_tests[*]}" "-S $TMPFILE"
+
+rm -f $TMPFILE
 
 exit $retval
diff --git a/test/test_build_command.vim b/test/test_build_command.vim
index d94e416..ac464e1 100644
--- a/test/test_build_command.vim
+++ b/test/test_build_command.vim
@@ -10,14 +10,14 @@ endfunction
 
 function! s:unit.test_build()
   edit test/data/without-cabal/Foo/Bar.hs
-  call self.assert.equal(['ghc-mod', 'do'], s:build())
+  call self.assert.equal(['ghc-mod', '--silent', '-b\\n', 'do'], s:build())
 endfunction
 
 function! s:unit.test_build_with_dist_dir()
   try
     call system('cd test/data/with-cabal; cabal configure; cabal build')
     edit test/data/with-cabal/src/Foo/Bar.hs
-    call self.assert.equal(['ghc-mod',
+    call self.assert.equal(['ghc-mod', '--silent', '-b\\n',
           \ '-g', '-i' . fnamemodify('test/data/with-cabal/dist/build/autogen', ':p:h'),
           \ '-g', '-I' . fnamemodify('test/data/with-cabal/dist/build/autogen', ':p:h'),
           \ '-g', '-optP-include',
@@ -34,7 +34,7 @@ function! s:unit.test_build_global_opt()
   let g:ghcmod_ghc_options = ['-Wall']
   try
     edit test/data/without-cabal/Main.hs
-    call self.assert.equal(['ghc-mod', '-g', '-Wall', 'do'], s:build())
+    call self.assert.equal(['ghc-mod', '--silent', '-b\\n', '-g', '-Wall', 'do'], s:build())
   finally
     unlet g:ghcmod_ghc_options
   endtry
@@ -46,7 +46,7 @@ function! s:unit.test_build_buffer_opt()
   let g:ghcmod_ghc_options = ['-Wall']
   try
     let b:ghcmod_ghc_options = ['-W']
-    call self.assert.equal(['ghc-mod', '-g', '-W', 'do'], s:build())
+    call self.assert.equal(['ghc-mod', '--silent', '-b\\n', '-g', '-W', 'do'], s:build())
   finally
     unlet g:ghcmod_ghc_options
   endtry
diff --git a/test/test_lint.vim b/test/test_lint.vim
index 099a4de..01aac06 100644
--- a/test/test_lint.vim
+++ b/test/test_lint.vim
@@ -59,7 +59,7 @@ function! s:unit.test_lint()
         \ 'lnum': 5,
         \ 'col': 9,
         \ 'filename': 'test/data/with-cabal/src/Foo/Bar.hs',
-        \ 'text': 'Redundant $',
+        \ 'text': 'Suggestion: Redundant $',
         \ }), l:qflist)
 endfunction
 
@@ -76,7 +76,7 @@ function! s:unit.test_lint_whitespace()
         \ 'lnum': 5,
         \ 'col': 9,
         \ 'filename': 'test/data/with whitespace/src/Foo/Bar.hs',
-        \ 'text': 'Redundant $',
+        \ 'text': 'Suggestion: Redundant $',
         \ }), l:qflist)
 endfunction
 
@@ -95,7 +95,7 @@ function! s:unit.test_lint_async()
           \ 'lnum': 5,
           \ 'col': 9,
           \ 'filename': 'test/data/with-cabal/src/Foo/Bar.hs',
-          \ 'text': 'Redundant $',
+          \ 'text': 'Suggestion: Redundant $',
           \ }), a:qflist)
   endfunction
   call s:async(l:callback)
@@ -111,7 +111,7 @@ function! s:unit.test_lint_opt()
           \ 'lnum': 5,
           \ 'col': 9,
           \ 'filename': 'test/data/with-cabal/src/Foo/Bar.hs',
-          \ 'text': 'Redundant $',
+          \ 'text': 'Suggestion: Redundant $',
           \ }), l:qflist)
   finally
     unlet g:ghcmod_hlint_options
@@ -130,7 +130,7 @@ function! s:unit.test_lint_async_opt()
           \ 'lnum': 5,
           \ 'col': 9,
           \ 'filename': 'test/data/with-cabal/src/Foo/Bar.hs',
-          \ 'text': 'Redundant $',
+          \ 'text': 'Suggestion: Redundant $',
           \ }), a:qflist)
   endfunction
   call s:async(l:callback)
diff --git a/test/test_type.vim b/test/test_type.vim
index 7e38c05..c6e8547 100644
--- a/test/test_type.vim
+++ b/test/test_type.vim
@@ -20,4 +20,10 @@ function! s:unit.test_type_compilation_failure()
   call self.assert.empty(l:types)
 endfunction
 
+function! s:unit.test_kill_recovery()
+  call s:unit.test_type()
+  call ghcmod#kill_modi(9)
+  call s:unit.test_type()
+endfunction
+
 call s:unit.run()