diff --git a/httplint/cli/http_parser.py b/httplint/cli/http_parser.py
index de0403f..ffc652f 100644
--- a/httplint/cli/http_parser.py
+++ b/httplint/cli/http_parser.py
@@ -38,7 +38,7 @@ def input_start(
         hdr_tuples: RawFieldListType,
         conn_tokens: List[bytes],
         transfer_codes: List[bytes],
-        content_length: int,
+        content_length: Optional[int],
     ) -> Tuple[bool, bool]:
         if self.mode == modes.REQUEST:
             self.linter = HttpRequestLinter(start_time=self.start_time)