diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 235aee2..1b04d02 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -726,6 +726,9 @@
 
   call CheckDefFailure("let x = &notexist", 'E113:')
   call CheckDefExecFailure("&grepprg = [343]", 'E1051:')
+
+  call CheckDefExecFailure("echo s:doesnt_exist", 'E121:')
+  call CheckDefExecFailure("echo g:doesnt_exist", 'E121:')
 endfunc
 
 let g:Funcrefs = [function('add')]
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 0e18e4a..1fb08ab 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -61,10 +61,10 @@
   assert_equal('foobar', $ENVVAR)
   $ENVVAR = ''
 
-  appendToMe ..= 'yyy'
-  assert_equal('xxxyyy', appendToMe)
-  addToMe += 222
-  assert_equal(333, addToMe)
+  s:appendToMe ..= 'yyy'
+  assert_equal('xxxyyy', s:appendToMe)
+  s:addToMe += 222
+  assert_equal(333, s:addToMe)
 enddef
 
 func Test_assignment_failure()