diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index e1d4853..c26f2af 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -579,6 +579,22 @@
 
   CheckScriptFailure(head + ["funcMap['func']('str', 123)"] + tail, 'E119:')
   CheckScriptFailure(head + ["funcMap['func']('str', 123, [1], 4)"] + tail, 'E118:')
+
+  var lines =<< trim END
+      vim9script
+      var Ref: func(number): any
+      Ref = (j) => !j
+      echo Ref(false)
+  END
+  CheckScriptFailure(lines, 'E1013: Argument 1: type mismatch, expected number but got bool', 4)
+
+  lines =<< trim END
+      vim9script
+      var Ref: func(number): any
+      Ref = (j) => !j
+      call Ref(false)
+  END
+  CheckScriptFailure(lines, 'E1013: Argument 1: type mismatch, expected number but got bool', 4)
 enddef
 
 def Test_call_lambda_args()