diff --git a/youtube_dl/__init__.py b/youtube_dl/__init__.py
index 7e156d4d4..63437301b 100644
--- a/youtube_dl/__init__.py
+++ b/youtube_dl/__init__.py
@@ -56,7 +56,6 @@ from .utils import (
     compat_print,
     DateRange,
     decodeOption,
-    determine_ext,
     get_term_width,
     DownloadError,
     get_cachedir,