diff --git a/openerp/import_xml.rng b/openerp/import_xml.rng
index 04922268e27..8584267a245 100644
--- a/openerp/import_xml.rng
+++ b/openerp/import_xml.rng
@@ -217,7 +217,14 @@
             <rng:optional><rng:attribute name="priority"/></rng:optional>
             <rng:choice>
                 <rng:group>
-                    <rng:optional><rng:attribute name="inherit_id"/></rng:optional>
+                    <rng:optional>
+                        <rng:attribute name="inherit_id"/>
+                        <rng:optional>
+                            <rng:attribute name="primary">
+                                <rng:value>True</rng:value>
+                            </rng:attribute>
+                        </rng:optional>
+                    </rng:optional>
                     <rng:optional><rng:attribute name="inherit_option_id"/></rng:optional>
                     <rng:optional><rng:attribute name="groups"/></rng:optional>
                 </rng:group>