diff --git a/protocol/rtp/rtp.go b/protocol/rtp/rtp.go
index 5805151b..1bbef690 100644
--- a/protocol/rtp/rtp.go
+++ b/protocol/rtp/rtp.go
@@ -64,7 +64,6 @@ type Pkt struct {
 // ExtensionHeader header provides fields for an RTP packet extension header.
 type ExtensionHeader struct {
 	ID     uint16
-	Len    uint16
 	Header [][4]byte
 }
 
@@ -73,10 +72,7 @@ func (p *Pkt) Bytes(buf []byte) []byte {
 	// Calculate the required length for the RTP packet.
 	headerExtensionLen := 0
 	if p.X {
-		if p.Extension.Len != uint16(len(p.Extension.Header)) {
-			panic("bad rtp packet extension length field")
-		}
-		headerExtensionLen = int(4 + 4*p.Extension.Len)
+		headerExtensionLen = int(4 + 4*len(p.Extension.Header))
 	}
 	requiredPktLen := defaultHeadSize + uint8(4*p.CC) + uint8(headerExtensionLen) + uint8(len(p.Payload)) + uint8(len(p.Padding))
 
@@ -110,12 +106,12 @@ func (p *Pkt) Bytes(buf []byte) []byte {
 	if p.X {
 		binary.BigEndian.PutUint16(buf[idx:idx+2], p.Extension.ID)
 		idx += 2
-		binary.BigEndian.PutUint16(buf[idx:idx+2], p.Extension.Len)
+		binary.BigEndian.PutUint16(buf[idx:idx+2], uint16(len(p.Extension.Header)))
 		idx += 2
-		for i := 0; i < int(p.Extension.Len); i++ {
+		for i := 0; i < len(p.Extension.Header); i++ {
 			copy(buf[idx+i*4:], p.Extension.Header[i][:])
 		}
-		idx += int(p.Extension.Len * 4)
+		idx += len(p.Extension.Header) * 4
 	}
 
 	// If there is payload, add to the buffer.
diff --git a/protocol/rtp/rtp_test.go b/protocol/rtp/rtp_test.go
index 3c6d07f9..2622fb81 100644
--- a/protocol/rtp/rtp_test.go
+++ b/protocol/rtp/rtp_test.go
@@ -156,8 +156,7 @@ var rtpTests = []struct {
 				{0x05, 0x06, 0x07, 0x08},
 			},
 			Extension: ExtensionHeader{
-				ID:  15,
-				Len: 2,
+				ID: 15,
 				Header: [][4]byte{
 					{0x01, 0x02, 0x03, 0x04},
 					{0x05, 0x06, 0x07, 0x08},