diff --git a/ch4-rpc/ch4-01-rpc-intro.md b/ch4-rpc/ch4-01-rpc-intro.md
index a03704a..5a877a0 100644
--- a/ch4-rpc/ch4-01-rpc-intro.md
+++ b/ch4-rpc/ch4-01-rpc-intro.md
@@ -78,7 +78,7 @@ type HelloServiceInterface = interface {
 }
 
 func RegisterHelloService(svc HelloServiceInterface) error {
-	rpc.RegisterName(HelloServiceName, svc)
+	return rpc.RegisterName(HelloServiceName, svc)
 }
 ```
 
@@ -117,11 +117,11 @@ func DialHelloService(network, address string) (*HelloServiceClient, error) {
 	if err != nil {
 		return nil, err
 	}
-	return &HelloServiceClient{Client: c}
+	return &HelloServiceClient{Client: c}, nil
 }
 
 func (p *HelloServiceClient) Hello(request string, reply *string) error {
-	return client.Call(HelloServiceName+".Hello", request, reply)
+	return p.Client.Call(HelloServiceName+".Hello", request, reply)
 }
 ```
 
diff --git a/examples/ch4-01-rpc-inro/hello-service-v2/api/hello.go b/examples/ch4-01-rpc-inro/hello-service-v2/api/hello.go
new file mode 100644
index 0000000..5795f8f
--- /dev/null
+++ b/examples/ch4-01-rpc-inro/hello-service-v2/api/hello.go
@@ -0,0 +1,31 @@
+package api
+
+import "net/rpc"
+
+const HelloServiceName = "path/to/pkg.HelloService"
+
+type HelloServiceInterface = interface {
+	Hello(request string, reply *string) error
+}
+
+func RegisterHelloService(svc HelloServiceInterface) error {
+	return rpc.RegisterName(HelloServiceName, svc)
+}
+
+type HelloServiceClient struct {
+	*rpc.Client
+}
+
+var _ HelloServiceInterface = (*HelloServiceClient)(nil)
+
+func DialHelloService(network, address string) (*HelloServiceClient, error) {
+	c, err := rpc.Dial(network, address)
+	if err != nil {
+		return nil, err
+	}
+	return &HelloServiceClient{Client: c}, nil
+}
+
+func (p *HelloServiceClient) Hello(request string, reply *string) error {
+	return p.Client.Call(HelloServiceName+".Hello", request, reply)
+}
diff --git a/examples/ch4-01-rpc-inro/hello-service-v2/client/main.go b/examples/ch4-01-rpc-inro/hello-service-v2/client/main.go
new file mode 100644
index 0000000..6362fd2
--- /dev/null
+++ b/examples/ch4-01-rpc-inro/hello-service-v2/client/main.go
@@ -0,0 +1,31 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/chai2010/advanced-go-programming-book/examples/ch4-01-rpc-inro/hello-service-v2/api"
+)
+
+type HelloService struct{}
+
+func (p *HelloService) Hello(request string, reply *string) error {
+	*reply = "hello:" + request
+	return nil
+}
+
+func main() {
+
+	client, err := api.DialHelloService("tcp", "localhost:1234")
+	if err != nil {
+		log.Fatal("dialing:", err)
+	}
+
+	var reply string
+	err = client.Hello("hello", &reply)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println(reply)
+}
diff --git a/examples/ch4-01-rpc-inro/hello-service-v2/server/main.go b/examples/ch4-01-rpc-inro/hello-service-v2/server/main.go
new file mode 100644
index 0000000..f6df3dc
--- /dev/null
+++ b/examples/ch4-01-rpc-inro/hello-service-v2/server/main.go
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"log"
+	"net"
+	"net/rpc"
+
+	"github.com/chai2010/advanced-go-programming-book/examples/ch4-01-rpc-inro/hello-service-v2/api"
+)
+
+type HelloService struct{}
+
+func (p *HelloService) Hello(request string, reply *string) error {
+	*reply = "hello:" + request
+	return nil
+}
+
+func main() {
+	api.RegisterHelloService(new(HelloService))
+
+	listener, err := net.Listen("tcp", ":1234")
+	if err != nil {
+		log.Fatal("ListenTCP error:", err)
+	}
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			log.Fatal("Accept error:", err)
+		}
+
+		go rpc.ServeConn(conn)
+	}
+}