diff --git a/youtube_dl/archive.py b/youtube_dl/archive.py
index e7940b9db..035a3c024 100644
--- a/youtube_dl/archive.py
+++ b/youtube_dl/archive.py
@@ -57,8 +57,7 @@ class Archive(object):
     def __contains__(self, item):
         if not isinstance(item, str):
             raise ValueError(
-                "An archive contains only strings. Provided {}".format(type(item))
-            )
+                "An archive contains only strings. Provided {}".format(type(item)))
 
         if item not in self._data:
             self._read_file()