diff --git a/swh/indexer/storage/__init__.py b/swh/indexer/storage/__init__.py
--- a/swh/indexer/storage/__init__.py
+++ b/swh/indexer/storage/__init__.py
@@ -13,7 +13,6 @@
 from swh.storage.common import db_transaction_generator, db_transaction
 from swh.storage.exc import StorageDBError
 from .db import Db
-from ..metadata_dictionary import MAPPINGS
 
 from . import converters
 
@@ -21,6 +20,9 @@
 INDEXER_CFG_KEY = 'indexer_storage'
 
 
+MAPPING_NAMES = ['codemeta', 'gemspec', 'maven', 'npm', 'pkg-info']
+
+
 def get_indexer_storage(cls, args):
     """Get an indexer storage object of class `storage_class` with
     arguments `storage_args`.
@@ -756,7 +758,7 @@
                   mapping. Note that indexing a given origin may use
                   0, 1, or many mappings.
         """
-        mapping_names = [m.name for m in MAPPINGS.values()]
+        mapping_names = [m for m in MAPPING_NAMES]
         select_parts = []
 
         # Count rows for each mapping
diff --git a/swh/indexer/storage/in_memory.py b/swh/indexer/storage/in_memory.py
--- a/swh/indexer/storage/in_memory.py
+++ b/swh/indexer/storage/in_memory.py
@@ -11,7 +11,7 @@
 import math
 import re
 
-from ..metadata_dictionary import MAPPINGS
+from . import MAPPING_NAMES
 
 SHA1_DIGEST_SIZE = 160
 
@@ -683,7 +683,7 @@
                   mapping. Note that indexing a given origin may use
                   0, 1, or many mappings.
         """
-        mapping_count = {m.name: 0 for m in MAPPINGS.values()}
+        mapping_count = {m: 0 for m in MAPPING_NAMES}
         total = non_empty = 0
         for data in self._origin_intrinsic_metadata.get_all():
             total += 1
diff --git a/swh/indexer/tests/storage/test_storage.py b/swh/indexer/tests/storage/test_storage.py
--- a/swh/indexer/tests/storage/test_storage.py
+++ b/swh/indexer/tests/storage/test_storage.py
@@ -11,12 +11,13 @@
 
 from swh.model.hashutil import hash_to_bytes
 
-from swh.indexer.storage import get_indexer_storage
+from swh.indexer.storage import get_indexer_storage, MAPPING_NAMES
 from swh.core.tests.db_testing import SingleDbTestFixture
 from swh.indexer.tests.storage.generate_data_test import (
     gen_content_mimetypes, gen_content_fossology_licenses
 )
 from swh.indexer.tests.storage import SQL_DIR
+from swh.indexer.metadata_dictionary import MAPPINGS
 
 TOOLS = [
     {
@@ -1594,3 +1595,7 @@
 
     """
     pass
+
+
+def test_mapping_names():
+    assert set(MAPPING_NAMES) == {m.name for m in MAPPINGS.values()}