diff --git a/swh/storage/filter.py b/swh/storage/filter.py
--- a/swh/storage/filter.py
+++ b/swh/storage/filter.py
@@ -92,7 +92,7 @@
             if content.sha256 in objects_seen:
                 continue
             objects_seen.add(content.sha256)
-            missing_contents.append(content.to_dict())
+            missing_contents.append(content.hashes())
 
         return set(self.storage.content_missing(
             missing_contents,
@@ -114,7 +114,7 @@
             if content.sha1_git is None or content.sha1_git in objects_seen:
                 continue
             objects_seen.add(content.sha1_git)
-            missing_contents.append(content.to_dict())
+            missing_contents.append(content.hashes())
 
         return {
             c.get('sha1_git')
diff --git a/swh/storage/in_memory.py b/swh/storage/in_memory.py
--- a/swh/storage/in_memory.py
+++ b/swh/storage/in_memory.py
@@ -259,7 +259,7 @@
         }
 
         missing_contents = self.skipped_content_missing(
-            [c.to_dict() for c in contents])
+            [c.hashes() for c in contents])
         missing = {self._content_key(c) for c in missing_contents}
         contents = [c for c in contents
                     if self._content_key(c) in missing]