diff --git a/src/testdir/test_let.vim b/src/testdir/test_let.vim
index 9a399e8..017b2a4 100644
--- a/src/testdir/test_let.vim
+++ b/src/testdir/test_let.vim
@@ -293,7 +293,7 @@
   let s = "var"
   let var = 1
   call assert_fails('let var += [1,2]', 'E734:')
-  call assert_fails('let {s}.1 = 2', 'E15:')
+  call assert_fails('let {s}.1 = 2', 'E18:')
   call assert_fails('let a[1] = 5', 'E121:')
   let l = [[1,2]]
   call assert_fails('let l[:][0] = [5]', 'E708:')
diff --git a/src/testdir/test_listdict.vim b/src/testdir/test_listdict.vim
index b064846..beeda2f 100644
--- a/src/testdir/test_listdict.vim
+++ b/src/testdir/test_listdict.vim
@@ -282,6 +282,13 @@
   call assert_equal('xxx3', Fn('xxx'))
 endfunc
 
+func Test_dict_assign()
+  let d = {}
+  let d.1 = 1
+  let d._ = 2
+  call assert_equal({'1': 1, '_': 2}, d)
+endfunc
+
 " Function in script-local List or Dict
 func Test_script_local_dict_func()
   let g:dict = {}
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index d7072f3..5b46c32 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -1310,6 +1310,11 @@
 		  ])
   assert_equal(1, d
   	.one)
+  d = {'1': 1, '_': 2}
+  assert_equal(1, d
+  	.1)
+  assert_equal(2, d
+  	._)
 
   # getting the one member should clear the dict after getting the item
   assert_equal('one', #{one: 'one'}.one)
@@ -1330,10 +1335,16 @@
       vim9script
       let d = #{one:
       		'one',
-		two: 'two'}
+		two: 'two',
+		1: 1,
+		_: 2}
       assert_equal('one', d.one)
       assert_equal('one', d
                             .one)
+      assert_equal(1, d
+                            .1)
+      assert_equal(2, d
+                            ._)
       assert_equal('one', d[
 			    'one'
 			    ])