diff --git a/nvchecker_source/manual.py b/nvchecker_source/manual.py
index d25c616..fbcc85b 100644
--- a/nvchecker_source/manual.py
+++ b/nvchecker_source/manual.py
@@ -2,4 +2,4 @@
 # Copyright (c) 2013-2020 lilydjwg <lilydjwg@gmail.com>, et al.
 
 async def get_version(name, conf, **kwargs):
-  return conf.get('manual').strip() or None
+  return str(conf.get('manual')).strip() or None