diff --git a/protocol/rtp/client.go b/protocol/rtp/client.go
index 4140abc1..22dd3d71 100644
--- a/protocol/rtp/client.go
+++ b/protocol/rtp/client.go
@@ -52,6 +52,7 @@ func NewClient(addr string, op func([]byte) ([]byte, error)) (*Client, error) {
 	c := &Client{
 		done: make(chan struct{}, 10),
 		ring: ring.NewBuffer(10, 4096, 0),
+		op:   op,
 	}
 
 	a, err := net.ResolveUDPAddr("udp", addr)