diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 94d23c6..9b5b4ff 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -1126,6 +1126,12 @@
 
   lines =<< trim END
       vim9script
+      echo {} - 22
+  END
+  CheckScriptFailure(lines, 'E731:', 2)
+
+  lines =<< trim END
+      vim9script
       echo 'abc' is? 'abc'
   END
   CheckScriptFailure(lines, 'E15:', 2)