diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,3 +1,3 @@
 swh.core
 swh.model >= 0.0.18
-swh.storage >= 0.0.97
+swh.storage >= 0.0.133
diff --git a/swh/loader/core/loader.py b/swh/loader/core/loader.py
--- a/swh/loader/core/loader.py
+++ b/swh/loader/core/loader.py
@@ -283,7 +283,7 @@
                 'swh_id': log_id
             })
 
-        tools = list(self.storage.tool_add([tool]))
+        tools = self.storage.tool_add([tool])
         tool_id = tools[0]['id']
 
         self.log.debug(