diff --git a/youtube_dl/extractor/ustream.py b/youtube_dl/extractor/ustream.py
index caf390f07..beac22264 100644
--- a/youtube_dl/extractor/ustream.py
+++ b/youtube_dl/extractor/ustream.py
@@ -72,7 +72,7 @@ class UstreamIE(InfoExtractor):
     @staticmethod
     def _extract_url(webpage):
         mobj = re.search(
-            r'<iframe[^>]+?src=(["\'])(?P<url>https?://www\.ustream\.tv/embed/.+?)\1', webpage)
+            r'<iframe[^>]+?src=(["\'])(?P<url>(?:https?:)?//www\.ustream\.tv/embed/.+?)\1', webpage)
         if mobj is not None:
             return mobj.group('url')