diff --git a/src/nonebot_plugins/trimo_plugin_msctconverter/msctexec.py b/src/nonebot_plugins/trimo_plugin_msctconverter/msctexec.py
index 52eeb48..badfefe 100644
--- a/src/nonebot_plugins/trimo_plugin_msctconverter/msctexec.py
+++ b/src/nonebot_plugins/trimo_plugin_msctconverter/msctexec.py
@@ -369,7 +369,7 @@ async def _():
             elif (
                 zhDateTime.DateTime.now()
                 - zhDateTime.DateTime(*filesaves[qqid][name]["date"])
-            ).seconds > cache_limit_data[os.path.splitext(name)[-1]][1]:
+            ).seconds > cache_limit_data[os.path.splitext(name)[-1].lower()][1]:
                 try:
                     os.remove(database_dir / qqid / name)
                 except: