diff --git a/recws.go b/recws.go
index 4fee538..5f579ea 100644
--- a/recws.go
+++ b/recws.go
@@ -98,7 +98,9 @@ func (rc *RecConn) ReadMessage() (messageType int, message []byte, err error) {
 func (rc *RecConn) WriteMessage(messageType int, data []byte) error {
 	err := ErrNotConnected
 	if rc.IsConnected() {
+		rc.mu.Lock()
 		err = rc.Conn.WriteMessage(messageType, data)
+		rc.mu.Unlock()
 		if err != nil {
 			rc.closeAndReconnect()
 		}
@@ -116,7 +118,9 @@ func (rc *RecConn) WriteMessage(messageType int, data []byte) error {
 func (rc *RecConn) WriteJSON(v interface{}) error {
 	err := ErrNotConnected
 	if rc.IsConnected() {
+		rc.mu.Lock()
 		err = rc.Conn.WriteJSON(v)
+		rc.mu.Unlock()
 		if err != nil {
 			rc.closeAndReconnect()
 		}
@@ -210,7 +214,6 @@ func (rc *RecConn) setDefaultHandshakeTimeout() {
 	}
 }
 
-
 func (rc *RecConn) setDefaultDialer(handshakeTimeout time.Duration) {
 	rc.mu.Lock()
 	defer rc.mu.Unlock()