diff --git a/odoo/addons/base/rng/calendar_view.rng b/odoo/addons/base/rng/calendar_view.rng
index 500a61b3389..656445e449e 100644
--- a/odoo/addons/base/rng/calendar_view.rng
+++ b/odoo/addons/base/rng/calendar_view.rng
@@ -19,6 +19,7 @@
             <rng:optional><rng:attribute name="quick_add" /></rng:optional>
             <rng:optional><rng:attribute name="color" /></rng:optional>
             <rng:optional><rng:attribute name="event_open_popup" /></rng:optional>
+            <rng:optional><rng:attribute name="js_class"/></rng:optional>
             <rng:optional>
                 <rng:attribute name="mode">
                     <rng:choice>