diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index ae813099d..88f9f9070 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -576,11 +576,9 @@ class ContentTooShortError(Exception):
     download is too small for what the server announced first, indicating
     the connection was probably interrupted.
     """
-    # Both in bytes
-    downloaded = None
-    expected = None
 
     def __init__(self, downloaded, expected):
+        # Both in bytes
         self.downloaded = downloaded
         self.expected = expected