diff --git a/pytchat/__init__.py b/pytchat/__init__.py
index d355558..bb241b5 100644
--- a/pytchat/__init__.py
+++ b/pytchat/__init__.py
@@ -2,7 +2,7 @@
 pytchat is a lightweight python library to browse youtube livechat without Selenium or BeautifulSoup.
 """
 __copyright__    = 'Copyright (C) 2019 taizan-hokuto'
-__version__      = '0.2.3'
+__version__      = '0.2.4'
 __license__      = 'MIT'
 __author__       = 'taizan-hokuto'
 __author_email__ = '55448286+taizan-hokuto@users.noreply.github.com'
diff --git a/pytchat/tool/extract/asyncdl.py b/pytchat/tool/extract/asyncdl.py
index c04b687..0a545e7 100644
--- a/pytchat/tool/extract/asyncdl.py
+++ b/pytchat/tool/extract/asyncdl.py
@@ -53,6 +53,7 @@ def _split(start, end, count, min_interval_sec=120):
 
 
 def ready_blocks(video_id, duration, div, callback):
+    param_set.clear()
     if div <= 0:
         raise ValueError