diff --git a/addons/mrp/models/mrp_workorder.py b/addons/mrp/models/mrp_workorder.py
index 650805dfda9..6b763deb29a 100644
--- a/addons/mrp/models/mrp_workorder.py
+++ b/addons/mrp/models/mrp_workorder.py
@@ -282,7 +282,9 @@ class MrpWorkorder(models.Model):
 
     @api.depends('date_planned_finished', 'production_id.date_planned_finished')
     def _compute_color(self):
-        late_orders = self.filtered(lambda x: x.production_id.date_planned_finished and x.date_planned_finished > x.production_id.date_planned_finished)
+        late_orders = self.filtered(lambda x: x.production_id.date_planned_finished
+                                              and x.date_planned_finished
+                                              and x.date_planned_finished > x.production_id.date_planned_finished)
         for order in late_orders:
             order.color = 4
         for order in (self - late_orders):