diff --git a/pep-0584.rst b/pep-0584.rst
index 34eb3960a..c47c84b19 100644
--- a/pep-0584.rst
+++ b/pep-0584.rst
@@ -175,6 +175,8 @@ accept any iterable, not just lists.  Continued from above::
     >>> d
     {'eggs': 2, 'cheese': 'cheddar', 'aardvark': 'Ethel', 'spam': 999}
 
+When new keys are added, their order matches their order within the
+right-hand mapping, if any exists for its type.
 
 ========================
 Reference Implementation