diff --git a/swh/storage/buffer.py b/swh/storage/buffer.py
--- a/swh/storage/buffer.py
+++ b/swh/storage/buffer.py
@@ -60,6 +60,8 @@
                 return partial(
                     self.object_add, object_type=object_type
                 )
+        if key == 'storage':
+            raise AttributeError(key)
         return getattr(self.storage, key)
 
     def content_add(self, content: Iterable[Dict]) -> Dict:
diff --git a/swh/storage/filter.py b/swh/storage/filter.py
--- a/swh/storage/filter.py
+++ b/swh/storage/filter.py
@@ -34,6 +34,8 @@
         }
 
     def __getattr__(self, key):
+        if key == 'storage':
+            raise AttributeError(key)
         return getattr(self.storage, key)
 
     def content_add(self, content: Iterable[Dict]) -> Dict:
diff --git a/swh/storage/objstorage.py b/swh/storage/objstorage.py
--- a/swh/storage/objstorage.py
+++ b/swh/storage/objstorage.py
@@ -21,6 +21,8 @@
         self.objstorage = get_objstorage(**objstorage_config)
 
     def __getattr__(self, key):
+        if key == 'objstorage':
+            raise AttributeError(key)
         return getattr(self.objstorage, key)
 
     def content_get(self, contents: Iterable[bytes]) -> Generator:
diff --git a/swh/storage/retry.py b/swh/storage/retry.py
--- a/swh/storage/retry.py
+++ b/swh/storage/retry.py
@@ -61,6 +61,8 @@
         self.storage = get_storage(**storage)
 
     def __getattr__(self, key):
+        if key == 'storage':
+            raise AttributeError(key)
         return getattr(self.storage, key)
 
     @swh_retry
diff --git a/swh/storage/validate.py b/swh/storage/validate.py
--- a/swh/storage/validate.py
+++ b/swh/storage/validate.py
@@ -46,6 +46,8 @@
         self.storage = get_storage(**storage)
 
     def __getattr__(self, key):
+        if key == 'storage':
+            raise AttributeError(key)
         return getattr(self.storage, key)
 
     def content_add(self, content: Iterable[Dict]) -> Dict: