diff --git a/libavformat/act.c b/libavformat/act.c
index 8dc6eb7f1c..8454cd1fc0 100644
--- a/libavformat/act.c
+++ b/libavformat/act.c
@@ -1,5 +1,5 @@
 /*
- * ACT file format muxer/demuxer
+ * ACT file format demuxer
  * Copyright (c) 2007-2008 Vladimir Voroshilov
  *
  * This file is part of FFmpeg.