diff --git a/borg/archive.py b/borg/archive.py
index 886060d1d..a133af7bb 100644
--- a/borg/archive.py
+++ b/borg/archive.py
@@ -755,6 +755,10 @@ def missing_chunk_detector(chunk_id):
                 for chunk_id, cdata in zip(items, repository.get_many(items)):
                     unpacker.feed(self.key.decrypt(chunk_id, cdata))
                     for item in unpacker:
+                        if not isinstance(item, dict):
+                            self.report_progress('Did not get expected metadata dict - archive corrupted!',
+                                                 error=True)
+                            continue
                         yield item
 
         repository = cache_if_remote(self.repository)
diff --git a/borg/cache.py b/borg/cache.py
index 1b66bc1b9..d64cdfb14 100644
--- a/borg/cache.py
+++ b/borg/cache.py
@@ -287,6 +287,9 @@ def fetch_and_build_idx(archive_id, repository, key, tmp_dir, tf_out):
                 add(chunk_idx, item_id, len(data), len(chunk))
                 unpacker.feed(data)
                 for item in unpacker:
+                    if not isinstance(item, dict):
+                        print('Error: Did not get expected metadata dict - archive corrupted!')
+                        continue
                     if b'chunks' in item:
                         for chunk_id, size, csize in item[b'chunks']:
                             add(chunk_idx, chunk_id, size, csize)