diff --git a/ocpp1.6_test/ocpp16_test.go b/ocpp1.6_test/ocpp16_test.go
index 4a826bd1..d913f0f2 100644
--- a/ocpp1.6_test/ocpp16_test.go
+++ b/ocpp1.6_test/ocpp16_test.go
@@ -93,7 +93,7 @@ func (websocketServer *MockWebsocketServer) NewClient(websocketId string, client
 	websocketServer.MethodCalled("NewClient", websocketId, client)
 }
 
-func (websocketServer *MockWebsocketServer) SetCheckClientHandler(handler func(id string, r *http.Request) bool) {
+func (websocketServer *MockWebsocketServer) SetCheckClientHandler(handler func(id string, r *http.Request) (string, bool)) {
 	websocketServer.CheckClientHandler = handler
 }
 
diff --git a/ocpp2.0.1_test/ocpp2_test.go b/ocpp2.0.1_test/ocpp2_test.go
index edf56201..0642cbc8 100644
--- a/ocpp2.0.1_test/ocpp2_test.go
+++ b/ocpp2.0.1_test/ocpp2_test.go
@@ -106,7 +106,7 @@ func (websocketServer *MockWebsocketServer) NewClient(websocketId string, client
 	websocketServer.MethodCalled("NewClient", websocketId, client)
 }
 
-func (websocketServer *MockWebsocketServer) SetCheckClientHandler(handler func(id string, r *http.Request) bool) {
+func (websocketServer *MockWebsocketServer) SetCheckClientHandler(handler func(id string, r *http.Request) (string, bool)) {
 	websocketServer.CheckClientHandler = handler
 }
 
diff --git a/ocppj/ocppj_test.go b/ocppj/ocppj_test.go
index e01cb257..dbaecec7 100644
--- a/ocppj/ocppj_test.go
+++ b/ocppj/ocppj_test.go
@@ -103,7 +103,7 @@ func (websocketServer *MockWebsocketServer) NewClient(websocketId string, client
 	websocketServer.MethodCalled("NewClient", websocketId, client)
 }
 
-func (websocketServer *MockWebsocketServer) SetCheckClientHandler(handler func(id string, r *http.Request) bool) {
+func (websocketServer *MockWebsocketServer) SetCheckClientHandler(handler func(id string, r *http.Request) (string, bool)) {
 	websocketServer.CheckClientHandler = handler
 }
 
diff --git a/ws/websocket.go b/ws/websocket.go
index fd8d6831..07fc03ec 100644
--- a/ws/websocket.go
+++ b/ws/websocket.go
@@ -160,7 +160,7 @@ func (e HttpConnectionError) Error() string {
 
 // ---------------------- SERVER ----------------------
 
-type CheckClientHandler func(id string, r *http.Request) bool
+type CheckClientHandler func(id string, r *http.Request) (string, bool)
 
 // WsServer defines a websocket server, which passively listens for incoming connections on ws or wss protocol.
 // The offered API are of asynchronous nature, and each incoming connection/message is handled using callbacks.
@@ -249,7 +249,7 @@ type WsServer interface {
 	SetCheckOriginHandler(handler func(r *http.Request) bool)
 	// SetCheckClientHandler sets a handler for validate incoming websocket connections, allowing to perform
 	// custom client connection checks.
-	SetCheckClientHandler(handler func(id string, r *http.Request) bool)
+	SetCheckClientHandler(handler func(id string, r *http.Request) (string, bool))
 	// Addr gives the address on which the server is listening, useful if, for
 	// example, the port is system-defined (set to 0).
 	Addr() *net.TCPAddr
@@ -262,7 +262,7 @@ type Server struct {
 	connections         map[string]*WebSocket
 	httpServer          *http.Server
 	messageHandler      func(ws Channel, data []byte) error
-	checkClientHandler  func(id string, r *http.Request) bool
+	checkClientHandler  func(id string, r *http.Request) (string, bool)
 	newClientHandler    func(ws Channel)
 	disconnectedHandler func(ws Channel)
 	basicAuthHandler    func(username string, password string) bool
@@ -319,7 +319,7 @@ func (server *Server) SetMessageHandler(handler func(ws Channel, data []byte) er
 	server.messageHandler = handler
 }
 
-func (server *Server) SetCheckClientHandler(handler func(id string, r *http.Request) bool) {
+func (server *Server) SetCheckClientHandler(handler func(id string, r *http.Request) (string, bool)) {
 	server.checkClientHandler = handler
 }
 
@@ -502,12 +502,15 @@ out:
 	}
 
 	if server.checkClientHandler != nil {
-		ok := server.checkClientHandler(id, r)
+		newId, ok := server.checkClientHandler(id, r)
 		if !ok {
 			server.error(fmt.Errorf("client validation: invalid client"))
 			http.Error(w, "Unauthorized", http.StatusUnauthorized)
 			return
 		}
+		if len(newId) > 0 {
+			id = newId
+		}
 	}
 
 	// Upgrade websocket
diff --git a/ws/websocket_test.go b/ws/websocket_test.go
index 399f7259..dbcf70c8 100644
--- a/ws/websocket_test.go
+++ b/ws/websocket_test.go
@@ -715,8 +715,8 @@ func TestCustomCheckClientHandler(t *testing.T) {
 	wsServer.SetNewClientHandler(func(ws Channel) {
 		connected <- true
 	})
-	wsServer.SetCheckClientHandler(func(clientId string, r *http.Request) bool {
-		return id == clientId
+	wsServer.SetCheckClientHandler(func(clientId string, r *http.Request) (string, bool) {
+		return clientId, id == clientId
 	})
 	go wsServer.Start(serverPort, serverPath)
 	time.Sleep(500 * time.Millisecond)