diff --git a/openerp/addons/base/ir/ir_model.py b/openerp/addons/base/ir/ir_model.py
index 395bf3e8d60..37d6e7a58cc 100644
--- a/openerp/addons/base/ir/ir_model.py
+++ b/openerp/addons/base/ir/ir_model.py
@@ -671,18 +671,20 @@ class ir_model_data(osv.osv):
         action_id = False
 
         if xml_id:
-            cr.execute('''SELECT imd.id, imd.res_id, md.id
+            cr.execute('''SELECT imd.id, imd.res_id, md.id, imd.model
                           FROM ir_model_data imd LEFT JOIN %s md ON (imd.res_id = md.id)
                           WHERE imd.module=%%s AND imd.name=%%s''' % model_obj._table,
                           (module, xml_id))
             results = cr.fetchall()
-            for imd_id2,res_id2,real_id2 in results:
+            for imd_id2,res_id2,real_id2,real_model in results:
                 if not real_id2:
                     self._get_id.clear_cache(self, uid, module, xml_id)
                     self.get_object_reference.clear_cache(self, uid, module, xml_id)
                     cr.execute('delete from ir_model_data where id=%s', (imd_id2,))
                     res_id = False
                 else:
+                    assert model == real_model, "External ID conflict, %s already refers to a `%s` record,"\
+                        " you can't define a `%s` record with this ID." % (xml_id, real_model, model)
                     res_id,action_id = res_id2,imd_id2
 
         if action_id and res_id: