diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,4 +1,4 @@
 swh.core >= 0.0.75
 swh.model >= 0.5.0
 swh.scheduler >= 0.4.0
-swh.storage >= 0.10.1
+swh.storage >= 0.12.0
diff --git a/swh/loader/package/deposit/loader.py b/swh/loader/package/deposit/loader.py
--- a/swh/loader/package/deposit/loader.py
+++ b/swh/loader/package/deposit/loader.py
@@ -8,7 +8,6 @@
 import logging
 import requests
 from typing import Any, Dict, Iterator, List, Mapping, Optional, Sequence, Tuple, Union
-import types
 
 import attr
 
@@ -209,17 +208,22 @@
                 return r
 
             snapshot_id = hash_to_bytes(r["snapshot_id"])
-            branches = self.storage.snapshot_get(snapshot_id)["branches"]
+            snapshot = self.storage.snapshot_get(snapshot_id)
+            if not snapshot:
+                return r
+            branches = snapshot["branches"]
             logger.debug("branches: %s", branches)
             if not branches:
                 return r
             rev_id = branches[b"HEAD"]["target"]
 
-            revisions = self.storage.revision_get([rev_id])
-            # FIXME: inconsistency between tests and production code
-            if isinstance(revisions, types.GeneratorType):
-                revisions = list(revisions)
+            revisions = list(self.storage.revision_get([rev_id]))
+            if not revisions:
+                return r
+
             revision = revisions[0]
+            if not revision:
+                return r
 
             # Retrieve the revision identifier
             dir_id = revision["directory"]
diff --git a/swh/loader/package/nixguix/tests/test_nixguix.py b/swh/loader/package/nixguix/tests/test_nixguix.py
--- a/swh/loader/package/nixguix/tests/test_nixguix.py
+++ b/swh/loader/package/nixguix/tests/test_nixguix.py
@@ -99,6 +99,7 @@
 
     revisions = storage.revision_get(revision_ids)
     for rev in revisions:
+        assert rev is not None
         metadata = rev["metadata"]
         raw = metadata["extrinsic"]["raw"]
         assert "url" in raw
diff --git a/swh/loader/tests/__init__.py b/swh/loader/tests/__init__.py
--- a/swh/loader/tests/__init__.py
+++ b/swh/loader/tests/__init__.py
@@ -180,6 +180,7 @@
             )
         # retrieve information from revision
         for rev in revisions:
+            assert rev is not None
             objects_by_target_type[TargetType.DIRECTORY].append(rev["directory"])
             object_to_branch[rev["directory"]] = rev["id"]