diff --git a/addons/mrp/models/mrp_workorder.py b/addons/mrp/models/mrp_workorder.py
index 0193535cca0..d438a7cb0e6 100644
--- a/addons/mrp/models/mrp_workorder.py
+++ b/addons/mrp/models/mrp_workorder.py
@@ -699,7 +699,7 @@ class MrpWorkorder(models.Model):
             if duration_expected_working < 0:
                 duration_expected_working = 0
             return alternative_workcenter.time_start + alternative_workcenter.time_stop + cycle_number * duration_expected_working * 100.0 / alternative_workcenter.time_efficiency
-        time_cycle = self.operation_id and self.operation_id.time_cycle or 60.0
+        time_cycle = self.operation_id.time_cycle
         return self.workcenter_id.time_start + self.workcenter_id.time_stop + cycle_number * time_cycle * 100.0 / self.workcenter_id.time_efficiency
 
     def _get_conflicted_workorder_ids(self):