diff --git a/packages/python/plotly/plotly/validators/layout/annotation/_ayref.py b/packages/python/plotly/plotly/validators/layout/annotation/_ayref.py
index d4c33be4776..bba53f39e33 100644
--- a/packages/python/plotly/plotly/validators/layout/annotation/_ayref.py
+++ b/packages/python/plotly/plotly/validators/layout/annotation/_ayref.py
@@ -8,7 +8,7 @@ def __init__(self, plotly_name="ayref", parent_name="layout.annotation", **kwarg
             parent_name=parent_name,
             edit_type=kwargs.pop("edit_type", "calc"),
             values=kwargs.pop(
-                "values", ["pixel", "/^y([2-9]|[1-9][0-9]+)?( domain)?$/"]
+                "values", ["pixel", "paper", "/^y([2-9]|[1-9][0-9]+)?( domain)?$/"]
             ),
             **kwargs,
         )