diff --git a/arkindex/ponos/api.py b/arkindex/ponos/api.py
index 60ae9d1725e7d16ef5f9fb8c0b73020af527e763..e27af396b7d0d5d4fc417f7a14f8c37bfcd0eb24 100644
--- a/arkindex/ponos/api.py
+++ b/arkindex/ponos/api.py
@@ -223,7 +223,7 @@ class TaskRestart(ProcessACLMixin, CreateAPIView):
             raise ValidationError(
                 detail="Task's state must be in a final state to be restarted."
             )
-        if len(Task.objects.filter(original_task=task)) > 0:
+        if task.restarts.exists():
             raise ValidationError(
                 detail="This task has already been restarted."
             )