diff --git a/src/testdir/test_const.vim b/src/testdir/test_const.vim
index 5eb2f69..c88efa6 100644
--- a/src/testdir/test_const.vim
+++ b/src/testdir/test_const.vim
@@ -215,6 +215,14 @@
 
   if 0 | lockvar x | endif
   let x = 'again'
+
+  let val = [1, 2, 3]
+  lockvar 0 val
+  let val[0] = 9
+  call assert_equal([9, 2, 3], val)
+  call add(val, 4)
+  call assert_equal([9, 2, 3, 4], val)
+  call assert_fails('let val = [4, 5, 6]', 'E1122:')
 endfunc