diff --git a/libavformat/swf.c b/libavformat/swf.c
index b19d6649e8..e9999f41b3 100644
--- a/libavformat/swf.c
+++ b/libavformat/swf.c
@@ -481,6 +481,8 @@ static int swf_read_header(AVFormatContext *s, AVFormatParameters *ap)
             get_byte(pb);
             v = get_byte(pb);
             get_le16(pb);
+            if (len!=4)
+                url_fskip(pb,len-4);
             /* if mp3 streaming found, OK */
             if ((v & 0x20) != 0) {
                 st = av_new_stream(s, 0);