diff --git a/codec.go b/codec.go
index c792abb..2f32a0b 100644
--- a/codec.go
+++ b/codec.go
@@ -11,8 +11,6 @@ import (
 	jsoniter "github.com/json-iterator/go"
 	"github.com/micro/go-micro/codec"
 	"github.com/micro/go-micro/codec/bytes"
-	"github.com/micro/go-micro/codec/jsonrpc"
-	"github.com/micro/go-micro/codec/protorpc"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/encoding"
 )
@@ -36,14 +34,6 @@ var (
 		"application/grpc+bytes":   bytesCodec{},
 	}
 
-	defaultRPCCodecs = map[string]codec.NewCodec{
-		"application/json":         jsonrpc.NewCodec,
-		"application/json-rpc":     jsonrpc.NewCodec,
-		"application/protobuf":     protorpc.NewCodec,
-		"application/proto-rpc":    protorpc.NewCodec,
-		"application/octet-stream": protorpc.NewCodec,
-	}
-
 	json = jsoniter.ConfigCompatibleWithStandardLibrary
 )
 
diff --git a/grpc.go b/grpc.go
index 62b8d5d..a593b69 100644
--- a/grpc.go
+++ b/grpc.go
@@ -282,16 +282,6 @@ func (g *grpcClient) newGRPCCodec(contentType string) (encoding.Codec, error) {
 	return nil, fmt.Errorf("Unsupported Content-Type: %s", contentType)
 }
 
-func (g *grpcClient) newCodec(contentType string) (codec.NewCodec, error) {
-	if c, ok := g.opts.Codecs[contentType]; ok {
-		return c, nil
-	}
-	if cf, ok := defaultRPCCodecs[contentType]; ok {
-		return cf, nil
-	}
-	return nil, fmt.Errorf("Unsupported Content-Type: %s", contentType)
-}
-
 func (g *grpcClient) Init(opts ...client.Option) error {
 	size := g.opts.PoolSize
 	ttl := g.opts.PoolTTL
diff --git a/grpc_pool_test.go b/grpc_pool_test.go
index 955e18c..d5c1fdb 100644
--- a/grpc_pool_test.go
+++ b/grpc_pool_test.go
@@ -1,11 +1,11 @@
 package grpc
 
 import (
+	"context"
 	"net"
 	"testing"
 	"time"
 
-	"context"
 	"google.golang.org/grpc"
 	pgrpc "google.golang.org/grpc"
 	pb "google.golang.org/grpc/examples/helloworld/helloworld"