diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 746983d..7e1e16a 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -53,8 +53,8 @@
   let RetThat: func = g:atrue ? RetOne : RetTwo
   assert_equal(function('len'), RetThat)
 
-  let x = FuncOne
-  let y = FuncTwo
+  let X = FuncOne
+  let Y = FuncTwo
   let Z = g:cond ? FuncOne : FuncTwo
   assert_equal(123, Z(3))
 enddef
@@ -132,8 +132,8 @@
 
   " missing argument detected even when common type is used
   call CheckDefFailure([
-	\ 'let x = FuncOne',
-	\ 'let y = FuncTwo',
+	\ 'let X = FuncOne',
+	\ 'let Y = FuncTwo',
 	\ 'let Z = g:cond ? FuncOne : FuncTwo',
 	\ 'Z()'], 'E119:')
 endfunc
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 10706b1..eedce32 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -28,6 +28,7 @@
   call CheckDefFailure(['let x:string'], 'E1069:')
   call CheckDefFailure(['let x:string = "x"'], 'E1069:')
   call CheckDefFailure(['let a:string = "x"'], 'E1069:')
+  call CheckDefFailure(['let lambda = {-> "lambda"}'], 'E704:')
 
   let nr: number = 1234
   call CheckDefFailure(['let nr: number = "asdf"'], 'E1013:')