diff --git a/swh/indexer/metadata_dictionary/composer.py b/swh/indexer/metadata_dictionary/composer.py
index 5d0f2ee..cd217df 100644
--- a/swh/indexer/metadata_dictionary/composer.py
+++ b/swh/indexer/metadata_dictionary/composer.py
@@ -1,56 +1,56 @@
 # Copyright (C) 2022  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
 
 import os.path
 
 from swh.indexer.codemeta import _DATA_DIR, SCHEMA_URI, _read_crosstable
 
-from .base import JsonMapping
+from .base import JsonMapping, SingleFileMapping
 
 COMPOSER_TABLE_PATH = os.path.join(_DATA_DIR, "composer.csv")
 
 with open(COMPOSER_TABLE_PATH) as fd:
     (CODEMETA_TERMS, COMPOSER_TABLE) = _read_crosstable(fd)
 
 
-class ComposerMapping(JsonMapping):
+class ComposerMapping(JsonMapping, SingleFileMapping):
     """Dedicated class for Packagist(composer.json) mapping and translation"""
 
     name = "composer"
     mapping = COMPOSER_TABLE["Composer"]
     filename = b"composer.json"
     string_fields = [
         "name",
         "description",
         "version",
         "keywords",
         "homepage",
         "license",
         "author",
         "authors",
     ]
 
     def normalize_homepage(self, s):
         if isinstance(s, str):
             return {"@id": s}
 
     def normalize_license(self, s):
         if isinstance(s, str):
             return {"@id": "https://spdx.org/licenses/" + s}
 
     def normalize_authors(self, author_list):
         authors = []
         for author in author_list:
             author_obj = {"@type": SCHEMA_URI + "Person"}
 
             if isinstance(author, dict):
                 if isinstance(author.get("name", None), str):
                     author_obj[SCHEMA_URI + "name"] = author.get("name", None)
                 if isinstance(author.get("email", None), str):
                     author_obj[SCHEMA_URI + "email"] = author.get("email", None)
 
                 authors.append(author_obj)
 
         return {"@list": authors}