diff --git a/ws_client/client.go b/ws_client/client.go
index dc560f1..620e62b 100644
--- a/ws_client/client.go
+++ b/ws_client/client.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"log"
 	"net/url"
+	"sync"
 
 	"git.lxtend.com/qqbot/action"
 	"git.lxtend.com/qqbot/constants"
@@ -16,6 +17,7 @@ type WebSocketClient struct {
 	conn   *websocket.Conn
 	closed bool
 	Done   chan struct{}
+	lock   sync.Mutex
 }
 
 func NewWebSocketClient(scheme, host, path string) (*WebSocketClient, error) {
@@ -88,6 +90,8 @@ func (c *WebSocketClient) receiveMessages() {
 }
 
 func (c *WebSocketClient) SendMessage(messageType int, message []byte) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
 	return c.conn.WriteMessage(messageType, message)
 }