diff --git a/addons/mrp/models/mrp_workorder.py b/addons/mrp/models/mrp_workorder.py
index 5ffb7ffc860..7d53543534b 100644
--- a/addons/mrp/models/mrp_workorder.py
+++ b/addons/mrp/models/mrp_workorder.py
@@ -545,7 +545,8 @@ class MrpWorkorder(models.Model):
             vals['leave_id'] = leave.id
             return self.write(vals)
         else:
-            vals['date_planned_start'] = start_date
+            if self.date_planned_start > start_date:
+                vals['date_planned_start'] = start_date
             if self.date_planned_finished < start_date:
                 vals['date_planned_finished'] = start_date
             return self.write(vals)