diff --git a/benchmark/benchmark.go b/benchmark/benchmark.go
index 574c4a92..56e2b78f 100644
--- a/benchmark/benchmark.go
+++ b/benchmark/benchmark.go
@@ -108,7 +108,6 @@ func StartServer(addr string, opts ...grpc.ServerOption) (string, func()) {
 }
 
 type byteBufServer struct {
-	reqSize  int32
 	respSize int32
 }
 
@@ -118,15 +117,16 @@ func (s *byteBufServer) UnaryCall(ctx context.Context, in *testpb.SimpleRequest)
 
 func (s *byteBufServer) StreamingCall(stream testpb.BenchmarkService_StreamingCallServer) error {
 	for {
-		m := make([]byte, s.reqSize)
-		err := stream.(grpc.ServerStream).RecvMsg(m)
+		var in []byte
+		err := stream.(grpc.ServerStream).RecvMsg(&in)
 		if err == io.EOF {
 			return nil
 		}
 		if err != nil {
 			return err
 		}
-		if err := stream.(grpc.ServerStream).SendMsg(make([]byte, s.respSize)); err != nil {
+		out := make([]byte, s.respSize)
+		if err := stream.(grpc.ServerStream).SendMsg(&out); err != nil {
 			return err
 		}
 	}
@@ -134,13 +134,13 @@ func (s *byteBufServer) StreamingCall(stream testpb.BenchmarkService_StreamingCa
 
 // StartbyteBufServer starts a benchmark service server that supports custom codec.
 // It returns its listen address and a function to stop the server.
-func StartByteBufServer(addr string, reqSize, respSize int32, opts ...grpc.ServerOption) (string, func()) {
+func StartByteBufServer(addr string, respSize int32, opts ...grpc.ServerOption) (string, func()) {
 	lis, err := net.Listen("tcp", addr)
 	if err != nil {
 		grpclog.Fatalf("Failed to listen: %v", err)
 	}
 	s := grpc.NewServer(opts...)
-	testpb.RegisterBenchmarkServiceServer(s, &byteBufServer{reqSize: reqSize, respSize: respSize})
+	testpb.RegisterBenchmarkServiceServer(s, &byteBufServer{respSize: respSize})
 	go s.Serve(lis)
 	return lis.Addr().String(), func() {
 		s.Stop()
@@ -180,11 +180,12 @@ func DoStreamingRoundTrip(stream testpb.BenchmarkService_StreamingCallClient, re
 
 // DoByteBufStreamingRoundTrip performs a round trip for a single streaming rpc, using custom codec.
 func DoByteBufStreamingRoundTrip(stream testpb.BenchmarkService_StreamingCallClient, reqSize, respSize int) error {
-	if err := stream.(grpc.ClientStream).SendMsg(make([]byte, reqSize)); err != nil {
+	out := make([]byte, reqSize)
+	if err := stream.(grpc.ClientStream).SendMsg(&out); err != nil {
 		return grpc.Errorf(grpc.Code(err), "StreamingCall(_).(ClientStream).SendMsg: %v", grpc.ErrorDesc(err))
 	}
-	m := make([]byte, respSize)
-	if err := stream.(grpc.ClientStream).RecvMsg(m); err != nil {
+	var in []byte
+	if err := stream.(grpc.ClientStream).RecvMsg(&in); err != nil {
 		return grpc.Errorf(grpc.Code(err), "StreamingCall(_).(ClientStream).RecvMsg: %v", grpc.ErrorDesc(err))
 	}
 	return nil
diff --git a/benchmark/worker/benchmark_server.go b/benchmark/worker/benchmark_server.go
index 1b58a854..5e2fd7b3 100644
--- a/benchmark/worker/benchmark_server.go
+++ b/benchmark/worker/benchmark_server.go
@@ -114,7 +114,7 @@ func startBenchmarkServerWithSetup(setup *testpb.ServerConfig, serverPort int) (
 		switch payload := setup.PayloadConfig.Payload.(type) {
 		case *testpb.PayloadConfig_BytebufParams:
 			opts = append(opts, grpc.CustomCodec(byteBufCodec{}))
-			addr, close = benchmark.StartByteBufServer(":"+strconv.Itoa(port), payload.BytebufParams.ReqSize, payload.BytebufParams.RespSize, opts...)
+			addr, close = benchmark.StartByteBufServer(":"+strconv.Itoa(port), payload.BytebufParams.RespSize, opts...)
 		case *testpb.PayloadConfig_SimpleParams:
 			addr, close = benchmark.StartServer(":"+strconv.Itoa(port), opts...)
 		case *testpb.PayloadConfig_ComplexParams:
diff --git a/benchmark/worker/main.go b/benchmark/worker/main.go
index 52990929..72ed63d4 100644
--- a/benchmark/worker/main.go
+++ b/benchmark/worker/main.go
@@ -35,6 +35,7 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"io"
 	"net"
 	"runtime"
@@ -56,11 +57,19 @@ type byteBufCodec struct {
 }
 
 func (byteBufCodec) Marshal(v interface{}) ([]byte, error) {
-	return v.([]byte), nil
+	b, ok := v.(*[]byte)
+	if !ok {
+		return nil, fmt.Errorf("Failed to marshal: %v is not type of *[]byte")
+	}
+	return *b, nil
 }
 
 func (byteBufCodec) Unmarshal(data []byte, v interface{}) error {
-	v = data
+	b, ok := v.(*[]byte)
+	if !ok {
+		return fmt.Errorf("Failed to marshal: %v is not type of *[]byte")
+	}
+	*b = data
 	return nil
 }