diff --git a/src/testdir/test_let.vim b/src/testdir/test_let.vim
index cfe095c..e0d543c 100644
--- a/src/testdir/test_let.vim
+++ b/src/testdir/test_let.vim
@@ -274,6 +274,7 @@
   call assert_fails('let &buftype[1] = "nofile"', 'E18:')
   let s = "var"
   let var = 1
+  call assert_fails('let var += [1,2]', 'E734:')
   call assert_fails('let {s}.1 = 2', 'E18:')
   call assert_fails('let a[1] = 5', 'E121:')
   let l = [[1,2]]
@@ -286,6 +287,8 @@
   call assert_fails('let l[0:1] = [1, 2, 3]', 'E710:')
   call assert_fails('let l[-2:-3] = [3, 4]', 'E684:')
   call assert_fails('let l[0:4] = [5, 6]', 'E711:')
+  call assert_fails('let g:["a;b"] = 10', 'E461:')
+  call assert_fails('let g:.min = function("max")', 'E704:')
 
   " This test works only when the language is English
   if v:lang == "C" || v:lang =~ '^[Ee]n'