diff --git a/addons/project/project.py b/addons/project/project.py
index 6b889b9760c..32103db56ef 100644
--- a/addons/project/project.py
+++ b/addons/project/project.py
@@ -134,11 +134,14 @@ class project(osv.osv):
 	def setActive(self, cr, uid, id, value, context={}):
 		proj = self.browse(cr, uid, id, context)
 		self.write(cr, uid, [id], {'active': value}, context)
+		cr.execute('select id from project_task where project_id=%d', (proj.id,))
+		tasks_id = [x[0] for x in cr.fetchall()]
 		self.pool.get('project.task').write(cr, uid,
-			[task.id for task in proj.tasks],
+			tasks_id,
 			{'active': value}, context)
-		for child in proj.child_id:
-			self.setActive(cr, uid, child.id, value, context)
+		project_ids = [x[0] for x in cr.fetchall()]
+		for child in project_ids:
+			self.setActive(cr, uid, child, value, context)
  		return True
 project()