diff --git a/server.py b/server.py
index b778cbfe3950a46fbecf20c96465f30558a2fe0a..abf6f4eb6f1aed1af5f2aca9505fd26c8116269d 100644
--- a/server.py
+++ b/server.py
@@ -450,7 +450,11 @@ def lecture(id, course=None, courseid=None):
 	if not courses:
 		return render_endpoint('courses', 'Diese Veranstaltung existiert nicht!'), 404
 	chapters = query('SELECT * FROM chapters WHERE lecture_id = ? AND NOT deleted AND (? OR visible) ORDER BY time ASC', id, ismod())
-	if not checkperm(perms):
+	username = password = None
+	if request.authorization:
+		username = request.authorization.username
+		password = request.authorization.password
+	if not checkperm(perms, username=username, password=password):
 		mode, text = permdescr(perms)
 		if mode == 'rwth':
 			flash(text+'. <a target="_blank" class="reloadonclose" href="'+url_for('start_rwthauth')+'">Hier authorisieren</a>.', category='player')