diff --git a/odoo/addons/base/rng/gantt_view.rng b/odoo/addons/base/rng/gantt_view.rng
index 7d9b2dcc00c..08e86b5bc87 100644
--- a/odoo/addons/base/rng/gantt_view.rng
+++ b/odoo/addons/base/rng/gantt_view.rng
@@ -11,6 +11,7 @@
             <rng:attribute name="date_start"/>
             <rng:attribute name="date_stop"/>
 
+            <rng:optional><rng:attribute name="js_class"/></rng:optional>
             <rng:optional><rng:attribute name="progress"/></rng:optional>
             <rng:optional><rng:attribute name="consolidation"/></rng:optional>
             <rng:optional><rng:attribute name="consolidation_max"/></rng:optional>