diff --git a/mm_index.py b/mm_index.py
index 2b5fdbe..8539e7e 100644
--- a/mm_index.py
+++ b/mm_index.py
@@ -12,8 +12,9 @@ import mm_users
 def iter_result_files(root: str) -> Iterable[str]:
     for dirpath, _dirnames, filenames in os.walk(root):
         for name in filenames:
-            if name.endswith(".json"):
-                yield os.path.join(dirpath, name)
+            if name == "users.json" or not name.endswith(".json"):
+                continue
+            yield os.path.join(dirpath, name)
 
 
 def parse_post_created(s: str) -> Optional[str]:
@@ -132,6 +133,9 @@ def load_posts(path: str) -> Optional[Tuple[Dict[str, Any], List[Dict[str, Any]]
     except (OSError, json.JSONDecodeError):
         return None
 
+    if not isinstance(data, dict):
+        return None
+
     channel_obj = data.get("channel")
     posts = data.get("posts")
     if not isinstance(channel_obj, dict) or not isinstance(posts, list):