diff --git a/swh/loader/package/storage.py b/swh/loader/package/storage.py
index 08782f1..ee2b64d 100644
--- a/swh/loader/package/storage.py
+++ b/swh/loader/package/storage.py
@@ -1,136 +1,133 @@
 # Copyright (C) 2019 The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 from swh.storage import get_storage
 
 from typing import Sequence, Dict
 
 
 class ProxyStorage:
     def __init__(self, **storage):
         self.storage = get_storage(**storage)
         self.contents_seen = set()
         self.directories_seen = set()
         self.revisions_seen = set()
 
     def origin_add(self, origins):
         return self.storage.origin_add(origins)
 
     def origin_visit_add(self, origin, date, type=None):
         return self.storage.origin_visit_add(origin, date, type=type)
 
     def _filter_missing_contents(
             self, content_hashes: Sequence[bytes]) -> Sequence[bytes]:
         """Return only the content keys missing from swh
 
         Args:
             content_hashes: List of sha256 to check for existence in swh
                 storage
 
         """
         missing_hashes = []
         for hash in content_hashes:
             if hash in self.contents_seen:
                 continue
             self.contents_seen.add(hash)
             missing_hashes.append({'sha256': hash})
 
         return list(self.storage.content_missing(
             missing_hashes,
             key_hash='sha256',
         ))
 
     def content_add(self, content: Sequence[Dict]) -> Dict:
         contents = list(content)
         missing_hashes = self._filter_missing_contents(
             c['sha256'] for c in contents
         )
         return self.storage.content_add(
             x for x in contents if x['sha256'] in missing_hashes
         )
 
-    def _filter_missing_directories(
-            self, directory_ids: Sequence[bytes]) -> Sequence[bytes]:
-        """Return only the content keys missing from swh
+    def _filter_missing_ids(
+            self,
+            object_type: str,
+            ids: Sequence[bytes]) -> Sequence[bytes]:
+        """Filter missing ids from the storage for a given object type.
 
         Args:
-            directory_ids: List of directory ids
+            object_type: object type to use {revision, directory}
+            ids: List of object_type ids
+
+        Returns:
+            Missing ids from the storage for object_type
 
         """
         missing_ids = []
-        for id in directory_ids:
+        for id in ids:
             if id in self.directories_seen:
                 continue
             self.directories_seen.add(id)
             missing_ids.append(id)
 
-        return list(self.storage.directory_missing(missing_ids))
+        fn_by_object_type = {
+            'revision': self.storage.revision_missing,
+            'directory': self.storage.directory_missing,
+        }
+        fn = fn_by_object_type[object_type]
+
+        return list(fn(missing_ids))
 
     def directory_add(self, directories: Sequence[Dict]) -> Dict:
         directories = list(directories)
-        missing_ids = self._filter_missing_directories(
-            d['id'] for d in directories
+        missing_ids = self._filter_missing_ids(
+            'directory',
+            (d['id'] for d in directories)
         )
         return self.storage.directory_add(
             d for d in directories if d['id'] in missing_ids
         )
 
-    def _filter_missing_revisions(
-            self, revision_ids: Sequence[bytes]) -> Sequence[bytes]:
-        """Return only the content keys missing from swh
-
-        Args:
-            revision_ids: List of revisions ids
-
-        """
-        missing_ids = []
-        for id in revision_ids:
-            if id in self.revisions_seen:
-                continue
-            self.revisions_seen.add(id)
-            missing_ids.append(id)
-
-        return list(self.storage.revision_missing(missing_ids))
-
     def revision_add(self, revisions):
         revisions = list(revisions)
-        missing_ids = self._filter_missing_revisions(
-            d['id'] for d in revisions
+        missing_ids = self._filter_missing_ids(
+            'revision',
+            (d['id'] for d in revisions)
         )
         return self.storage.revision_add(
             r for r in revisions if r['id'] in missing_ids
         )
 
     def snapshot_add(self, snapshots):
         return self.storage.snapshot_add(snapshots)
 
     def origin_visit_update(self, origin, visit_id, status=None,
                             metadata=None, snapshot=None):
         return self.storage.origin_visit_update(
             origin, visit_id, status=status,
             metadata=metadata, snapshot=snapshot
         )
 
     def stat_counters(self):
         return self.storage.stat_counters()
 
     def origin_visit_get(self, origin, last_visit=None, limit=None):
         return self.storage.origin_visit_get(
             origin, last_visit=last_visit, limit=limit)
 
     def content_missing_per_sha1(self, contents):
         yield from self.storage.content_missing_per_sha1(contents)
 
     def directory_missing(self, directories):
         return self.storage.directory_missing(directories)
 
     def revision_missing(self, revisions):
         return self.storage.revision_missing(revisions)
 
     def snapshot_get(self, snapshot_id):
         return self.storage.snapshot_get(snapshot_id)
 
     def content_get(self, content):
         return self.storage.content_get(content)