diff --git a/swh/indexer/indexer.py b/swh/indexer/indexer.py
--- a/swh/indexer/indexer.py
+++ b/swh/indexer/indexer.py
@@ -261,7 +261,7 @@
                                 by index function.
             task (dict): a dict in the form expected by
                         `scheduler.backend.SchedulerBackend.create_tasks`
-                        without `next_run`, plus a `result_name` key.
+                        without `next_run`, plus an optional `result_name` key.
 
         Returns:
             None
@@ -273,9 +273,10 @@
             else:
                 scheduler = get_scheduler(**self.config['scheduler'])
             task = deepcopy(task)
-            result_name = task.pop('result_name')
+            result_name = task.pop('result_name', None)
             task['next_run'] = datetime.datetime.now()
-            task['arguments']['kwargs'][result_name] = self.results
+            if result_name:
+                task['arguments']['kwargs'][result_name] = self.results
             scheduler.create_tasks([task])
 
     @abc.abstractmethod
@@ -339,7 +340,7 @@
                                  them
             next_step (dict): a dict in the form expected by
                         `scheduler.backend.SchedulerBackend.create_tasks`
-                        without `next_run`, plus a `result_name` key.
+                        without `next_run`, plus an optional `result_name` key.
             **kwargs: passed to the `index` method
 
         """
@@ -503,7 +504,7 @@
                                    or ignore them
             next_step (dict): a dict in the form expected by
                         `scheduler.backend.SchedulerBackend.create_tasks`
-                        without `next_run`, plus a `result_name` key.
+                        without `next_run`, plus an optional `result_name` key.
             parse_ids (bool): Do we need to parse id or not (default)
             **kwargs: passed to the `index` method