diff --git a/rtmp/flv/writer.go b/rtmp/flv/writer.go
index e70d842..492f601 100644
--- a/rtmp/flv/writer.go
+++ b/rtmp/flv/writer.go
@@ -35,13 +35,21 @@ func (writer *FLVWriter) WriteMetadataTag(data *[]byte) (err error) {
 	binary.BigEndian.PutUint32(uint24_buf, uint32(len((*data)[16:])))
 	copy(tag_header[1:4], uint24_buf[1:])
 
-	_, err = writer.w.Write(tag_header)
-	if err == nil {
-		_, err = writer.w.Write((*data)[16:])
+	if _, err = writer.w.Write(tag_header); err != nil {
+		return
 	}
-	return
+	if _, err = writer.w.Write((*data)[16:]); err != nil {
+		return
+	}
+
+
+	tag_len_buf := make([]byte, 4)
+	binary.BigEndian.PutUint32(tag_len_buf, uint32(len((*data)[16:]) + 11))
+	_, err = writer.w.Write(tag_len_buf)
+	return	
 }
 
+
 func (writer *FLVWriter) write_flv_header() (err error) {
 	header := make([]byte, 13)
 	copy(header[:3], "FLV")