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
@@ -7,7 +7,7 @@
 from collections import Counter, defaultdict
 import itertools
 import json
-from typing import Dict, Iterable, Iterator, List, Optional, Tuple
+from typing import Dict, Iterable, List, Optional, Tuple
 
 import psycopg2
 import psycopg2.pool
@@ -146,7 +146,7 @@
     @db_transaction_generator()
     def content_mimetype_missing(
         self, mimetypes: Iterable[Dict], db=None, cur=None
-    ) -> Iterator[Tuple[Sha1, int]]:
+    ) -> Iterable[Tuple[Sha1, int]]:
         for obj in db.content_mimetype_missing_from_list(mimetypes, cur):
             yield obj[0]
 
@@ -276,7 +276,7 @@
     @db_transaction_generator()
     def content_mimetype_get(
         self, ids: Iterable[Sha1], db=None, cur=None
-    ) -> Iterator[ContentMimetypeRow]:
+    ) -> Iterable[ContentMimetypeRow]:
         for c in db.content_mimetype_get_from_list(ids, cur):
             yield ContentMimetypeRow.from_dict(
                 converters.db_to_mimetype(dict(zip(db.content_mimetype_cols, c)))
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
@@ -259,7 +259,7 @@
 
     def content_mimetype_missing(
         self, mimetypes: Iterable[Dict]
-    ) -> Iterator[Tuple[Sha1, int]]:
+    ) -> Iterable[Tuple[Sha1, int]]:
         yield from self._mimetypes.missing(mimetypes)
 
     def content_mimetype_get_partition(
@@ -280,7 +280,7 @@
         added = self._mimetypes.add(mimetypes, conflict_update)
         return {"content_mimetype:add": added}
 
-    def content_mimetype_get(self, ids: Iterable[Sha1]) -> Iterator[ContentMimetypeRow]:
+    def content_mimetype_get(self, ids: Iterable[Sha1]) -> Iterable[ContentMimetypeRow]:
         yield from self._mimetypes.get(ids)
 
     def content_language_missing(self, languages):
diff --git a/swh/indexer/storage/interface.py b/swh/indexer/storage/interface.py
--- a/swh/indexer/storage/interface.py
+++ b/swh/indexer/storage/interface.py
@@ -3,7 +3,7 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-from typing import Dict, Iterable, Iterator, List, Optional, Tuple, TypeVar
+from typing import Dict, Iterable, List, Optional, Tuple, TypeVar
 
 from swh.core.api import remote_api_endpoint
 from swh.core.api.classes import PagedResult as CorePagedResult
@@ -25,7 +25,7 @@
     @remote_api_endpoint("content_mimetype/missing")
     def content_mimetype_missing(
         self, mimetypes: Iterable[Dict]
-    ) -> Iterator[Tuple[Sha1, int]]:
+    ) -> Iterable[Tuple[Sha1, int]]:
         """Generate mimetypes missing from storage.
 
         Args:
@@ -90,7 +90,7 @@
         ...
 
     @remote_api_endpoint("content_mimetype")
-    def content_mimetype_get(self, ids: Iterable[Sha1]) -> Iterator[ContentMimetypeRow]:
+    def content_mimetype_get(self, ids: Iterable[Sha1]) -> Iterable[ContentMimetypeRow]:
         """Retrieve full content mimetype per ids.
 
         Args: