diff --git a/internal/cli/universal_login_customize.go b/internal/cli/universal_login_customize.go
index 2b2a8c529..bf6c595d6 100644
--- a/internal/cli/universal_login_customize.go
+++ b/internal/cli/universal_login_customize.go
@@ -49,6 +49,10 @@ type (
 		CustomText map[string]interface{} `json:"custom_text,omitempty"`
 	}
 
+	errorData struct {
+		Error string `json:"error"`
+	}
+
 	webSocketHandler struct {
 		shutdown     context.CancelFunc
 		display      *display.Renderer
@@ -57,11 +61,69 @@ type (
 	}
 
 	webSocketMessage struct {
-		Type    string          `json:"type"`
-		Payload json.RawMessage `json:"payload"`
+		Type    string      `json:"type"`
+		Payload interface{} `json:"-"`
 	}
 )
 
+// MarshalJSON implements the json.Marshaler interface.
+func (m *webSocketMessage) MarshalJSON() ([]byte, error) {
+	type message webSocketMessage
+	type messageWrapper struct {
+		*message
+		RawPayload json.RawMessage `json:"payload"`
+	}
+
+	w := &messageWrapper{(*message)(m), nil}
+
+	if m.Payload != nil {
+		b, err := json.Marshal(m.Payload)
+		if err != nil {
+			return nil, err
+		}
+
+		w.RawPayload = b
+	}
+
+	return json.Marshal(w)
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface.
+func (m *webSocketMessage) UnmarshalJSON(b []byte) error {
+	type message webSocketMessage
+	type messageWrapper struct {
+		*message
+		RawPayload json.RawMessage `json:"payload"`
+	}
+
+	w := &messageWrapper{(*message)(m), nil}
+
+	if err := json.Unmarshal(b, w); err != nil {
+		return err
+	}
+
+	var payload interface{}
+
+	switch m.Type {
+	case loadBrandingMessageType, saveBrandingMessageType:
+		payload = &universalLoginBrandingData{}
+	case fetchPromptMessageType:
+		payload = &promptData{}
+	default:
+		payload = make(map[string]interface{})
+	}
+
+	if w.RawPayload != nil {
+		if err := json.Unmarshal(w.RawPayload, &payload); err != nil {
+			return err
+		}
+	}
+
+	m.Payload = payload
+
+	return nil
+}
+
 func customizeUniversalLoginCmd(cli *cli) *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "customize",
@@ -354,20 +416,12 @@ func (h *webSocketHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	connection.SetReadLimit(1e+6) // 1 MB.
 
-	payload, err := json.Marshal(&h.brandingData)
-	if err != nil {
-		h.display.Errorf("Failed to encode the branding data to json: %v", err)
-		h.display.Warnf("Try restarting the command.")
-		h.shutdown()
-		return
-	}
-
 	loadBrandingMsg := webSocketMessage{
 		Type:    loadBrandingMessageType,
-		Payload: payload,
+		Payload: h.brandingData,
 	}
 
-	if err = connection.WriteJSON(loadBrandingMsg); err != nil {
+	if err = connection.WriteJSON(&loadBrandingMsg); err != nil {
 		h.display.Errorf("Failed to send branding data message: %v", err)
 		h.display.Warnf("Try restarting the command.")
 		h.shutdown()
@@ -389,9 +443,9 @@ func (h *webSocketHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 		switch message.Type {
 		case fetchPromptMessageType:
-			var promptToFetch promptData
-			if err := json.Unmarshal(message.Payload, &promptToFetch); err != nil {
-				h.display.Errorf("Failed to unmarshal fetch prompt payload: %v", err)
+			promptToFetch, ok := message.Payload.(*promptData)
+			if !ok {
+				h.display.Errorf("Invalid payload type: %T", message.Payload)
 				continue
 			}
 
@@ -405,49 +459,46 @@ func (h *webSocketHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				h.display.Errorf("Failed to fetch custom text for prompt: %v", err)
 
 				errorMsg := webSocketMessage{
-					Type:    errorMessageType,
-					Payload: []byte(fmt.Sprintf(`{"error":%q}`, err.Error())),
+					Type: errorMessageType,
+					Payload: &errorData{
+						Error: err.Error(),
+					},
 				}
 
-				if err := connection.WriteJSON(errorMsg); err != nil {
+				if err := connection.WriteJSON(&errorMsg); err != nil {
 					h.display.Errorf("Failed to send error message: %v", err)
 				}
 
 				continue
 			}
 
-			payload, err := json.Marshal(promptToSend)
-			if err != nil {
-				h.display.Errorf("failed to encode the branding data to json: %v", err)
-				h.shutdown()
-				return
-			}
-
 			fetchPromptMsg := webSocketMessage{
 				Type:    fetchPromptMessageType,
-				Payload: payload,
+				Payload: promptToSend,
 			}
 
-			if err = connection.WriteJSON(fetchPromptMsg); err != nil {
+			if err = connection.WriteJSON(&fetchPromptMsg); err != nil {
 				h.display.Errorf("Failed to send prompt data message: %v", err)
 				continue
 			}
 		case saveBrandingMessageType:
-			var saveBrandingMsg universalLoginBrandingData
-			if err := json.Unmarshal(message.Payload, &saveBrandingMsg); err != nil {
-				h.display.Errorf("Failed to unmarshal save branding data payload: %v", err)
+			saveBrandingMsg, ok := message.Payload.(*universalLoginBrandingData)
+			if !ok {
+				h.display.Errorf("Invalid payload type: %T", message.Payload)
 				continue
 			}
 
-			if err := saveUniversalLoginBrandingData(r.Context(), h.api, &saveBrandingMsg); err != nil {
+			if err := saveUniversalLoginBrandingData(r.Context(), h.api, saveBrandingMsg); err != nil {
 				h.display.Errorf("Failed to save branding data: %v", err)
 
 				errorMsg := webSocketMessage{
-					Type:    errorMessageType,
-					Payload: []byte(fmt.Sprintf(`{"error":%q}`, err.Error())),
+					Type: errorMessageType,
+					Payload: &errorData{
+						Error: err.Error(),
+					},
 				}
 
-				if err := connection.WriteJSON(errorMsg); err != nil {
+				if err := connection.WriteJSON(&errorMsg); err != nil {
 					h.display.Errorf("Failed to send error message: %v", err)
 				}