diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index 206dd56bc..1dc3153fd 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -619,7 +619,7 @@ def _create_http_connection(ydl_handler, http_class, is_https, *args, **kwargs):
     # expected HTTP responses to meet HTTP/1.0 or later (see also
     # https://github.com/rg3/youtube-dl/issues/6727)
     if sys.version_info < (3, 0):
-        kwargs['strict'] = True
+        kwargs[b'strict'] = True
     hc = http_class(*args, **kwargs)
     source_address = ydl_handler._params.get('source_address')
     if source_address is not None: