diff --git a/src/testdir/test_unlet.vim b/src/testdir/test_unlet.vim
index 4c58785..c20b0be 100644
--- a/src/testdir/test_unlet.vim
+++ b/src/testdir/test_unlet.vim
@@ -17,3 +17,7 @@
   unlet! does_not_exist
   call assert_fails('unlet does_not_exist', 'E108:')
 endfunc
+
+func Test_unlet_fails()
+  call assert_fails('unlet v:["count"]', 'E46:')
+endfunc