diff --git a/session.go b/session.go
index 994d42d..19c0b27 100755
--- a/session.go
+++ b/session.go
@@ -128,6 +128,7 @@ func (session *Session) Send(msg interface{}) error {
 
 	session.sendMutex.RLock()
 	if session.IsClosed() {
+		session.sendMutex.RUnlock()
 		return SessionClosedError
 	}