diff --git a/openerp/addons/base/ir/osv_memory_autovacuum.py b/openerp/addons/base/ir/osv_memory_autovacuum.py
index 1231ef5f233..975fcd0a403 100644
--- a/openerp/addons/base/ir/osv_memory_autovacuum.py
+++ b/openerp/addons/base/ir/osv_memory_autovacuum.py
@@ -28,6 +28,6 @@ class osv_memory_autovacuum(openerp.osv.osv.osv_memory):
     def power_on(self, cr, uid, context=None):
         for model in self.pool.models.values():
             if model.is_transient():
-                obj._transient_vacuum(cr, uid)
+                model._transient_vacuum(cr, uid)
         return True