diff --git a/src/hb-aat-layout-kerx-table.hh b/src/hb-aat-layout-kerx-table.hh
index db6bba4a7..6a793a3e4 100644
--- a/src/hb-aat-layout-kerx-table.hh
+++ b/src/hb-aat-layout-kerx-table.hh
@@ -324,6 +324,7 @@ struct kerx
       if (reverse)
         c->buffer->reverse ();
 
+      /* XXX Reverse-kern is not working yet... */
       table->dispatch (c);
 
       if (reverse)