diff --git a/src/snmalloc/backend_helpers/lockrange.h b/src/snmalloc/backend_helpers/lockrange.h
index a2b3811..ce91711 100644
--- a/src/snmalloc/backend_helpers/lockrange.h
+++ b/src/snmalloc/backend_helpers/lockrange.h
@@ -7,6 +7,9 @@ namespace snmalloc
 {
   /**
    * Protect the ParentRange with a spin lock.
+   *
+   * Accesses via the ancestor() mechanism will bypass the lock and so
+   * should be used only where the resulting data races are acceptable.
    */
   struct LockRange
   {