diff --git a/swh/loader/pypi/loader.py b/swh/loader/pypi/loader.py
--- a/swh/loader/pypi/loader.py
+++ b/swh/loader/pypi/loader.py
@@ -113,7 +113,7 @@
         # retrieve only revisions (e.g the alias we do not want here)
         revs = [rev['target']
                 for rev in last_snapshot['branches'].values()
-                if rev['target_type'] == 'revision']
+                if rev and rev['target_type'] == 'revision']
         known_revisions = self.storage.revision_get(revs)
         ret = {}
         for revision in known_revisions: