diff --git a/openerp/addons/base/rng/view.rng b/openerp/addons/base/rng/view.rng
index 54d08edc596..a218cb55f5d 100644
--- a/openerp/addons/base/rng/view.rng
+++ b/openerp/addons/base/rng/view.rng
@@ -655,6 +655,7 @@
             <rng:optional><rng:attribute name="context"/></rng:optional>
             <rng:optional><rng:attribute name="confirm"/></rng:optional>
             <rng:optional><rng:attribute name="help"/></rng:optional>
+            <rng:optional><rng:attribute name="class"/></rng:optional>
             <rng:optional><rng:attribute name="default_focus"/></rng:optional>
             <rng:zeroOrMore>
                 <rng:choice>