diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index 0a94734..eddc8c5 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -740,6 +740,22 @@
 
   CheckDefFailure(['var lines =<< trim END X', 'END'], 'E488:')
   CheckDefFailure(['var lines =<< trim END " comment', 'END'], 'E488:')
+
+  lines =<< trim [END]
+      def Func()
+        var&lines =<< trim END
+        x
+        x
+        x
+        x
+        x
+        x
+        x
+        x
+      enddef
+      call Func()
+  [END]
+  CheckScriptFailure(lines, 'E990:')
 enddef
 
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker