diff --git a/project_task_line/models/project.py b/project_task_line/models/project.py
index 887f53ab..3557f69c 100644
--- a/project_task_line/models/project.py
+++ b/project_task_line/models/project.py
@@ -12,7 +12,7 @@ class ProjectTask(models.Model):
         for task in self:
             subtasks = task._get_all_subtasks()
             task.subtask_count = len(subtasks)
-            task.subtask_count_done = len(subtasks.filtered(lambda t: t.stage_id.is_closed))
+            task.subtask_count_done = len(subtasks.filtered(lambda t: t.is_closed))
     
     def action_subtask(self):
         action = self.env.ref('project.action_view_all_task').sudo().read()[0]