diff --git a/src/testdir/test_stat.vim b/src/testdir/test_stat.vim
index 5cd82b8..b565281 100644
--- a/src/testdir/test_stat.vim
+++ b/src/testdir/test_stat.vim
@@ -76,6 +76,39 @@
   call delete(fname)
 endfunc
 
+func Test_checktime_fast()
+  CheckFeature nanotime
+
+  let fname = 'Xtest.tmp'
+
+  let fl = ['Hello World!']
+  call writefile(fl, fname)
+  set autoread
+  exec 'e' fname
+  let fl = readfile(fname)
+  let fl[0] .= ' - checktime'
+  call writefile(fl, fname)
+  checktime
+  call assert_equal(fl[0], getline(1))
+
+  call delete(fname)
+endfunc
+
+func Test_autoread_fast()
+  CheckFeature nanotime
+
+  new Xautoread
+  set autoread
+  call setline(1, 'foo')
+
+  w!
+  silent !echo bar > Xautoread
+  checktime
+
+  call assert_equal('bar', trim(getline(1)))
+  call delete('Xautoread')
+endfunc
+
 func Test_autoread_file_deleted()
   new Xautoread
   set autoread