diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index 3bb289b..c228f26 100644
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -238,6 +238,24 @@
   lines =<< trim END
       vim9script
 
+      class Class
+          this.id: string
+          def Method1()
+              echo 'Method1' .. this.id
+          enddef
+      endclass
+
+      var obj: Class
+      def Func()
+          obj.Method1()
+      enddef
+      Func()
+  END
+  v9.CheckScriptFailure(lines, 'E1360:')
+
+  lines =<< trim END
+      vim9script
+
       class Background
         this.background = 'dark'
       endclass