diff --git a/addons/crm/crm_lead.py b/addons/crm/crm_lead.py
index cb21f7a3978..c5aa47fa244 100644
--- a/addons/crm/crm_lead.py
+++ b/addons/crm/crm_lead.py
@@ -957,7 +957,7 @@ class crm_lead(format_address, osv.osv):
         lead = self.browse(cr, uid, id, context=context)
         local_context = dict(context)
         local_context.setdefault('default_type', lead.type)
-        local_context.setdefault('default_section_id', lead.section_id)
+        local_context.setdefault('default_section_id', lead.section_id.id)
         if lead.type == 'opportunity':
             default['date_open'] = fields.datetime.now()
         else:
diff --git a/openerp/osv/expression.py b/openerp/osv/expression.py
index 8515c659805..9bf4083769d 100644
--- a/openerp/osv/expression.py
+++ b/openerp/osv/expression.py
@@ -1108,6 +1108,8 @@ class expression(object):
             "Invalid operator %r in domain term %r" % (operator, leaf)
         assert leaf in (TRUE_LEAF, FALSE_LEAF) or left in model._all_columns \
             or left in MAGIC_COLUMNS, "Invalid field %r in domain term %r" % (left, leaf)
+        assert not isinstance(right, BaseModel), \
+            "Invalid value %r in domain term %r" % (right, leaf)
 
         table_alias = '"%s"' % (eleaf.generate_alias())