diff --git a/youtube_dl/extractor/safari.py b/youtube_dl/extractor/safari.py
index 6356cf95e..4942437c7 100644
--- a/youtube_dl/extractor/safari.py
+++ b/youtube_dl/extractor/safari.py
@@ -166,7 +166,7 @@ class SafariIE(SafariBaseIE):
                 '%s/player/kaltura_session/?reference_id=%s' % (self._API_BASE, reference_id),
                 video_id, 'Downloading kaltura session JSON',
                 'Unable to download kaltura session JSON', fatal=False,
-                headers={'accept': 'application/json'})
+                headers={'Accept': 'application/json'})
             if kaltura_session:
                 session = kaltura_session.get('session')
                 if session: