diff --git a/mqtt/client.go b/mqtt/client.go
index 625752f..94b4715 100644
--- a/mqtt/client.go
+++ b/mqtt/client.go
@@ -75,6 +75,9 @@ func MqttClientSubscribe(session *Session, topic string, qos byte) {
 }
 
 func MqttClientUnsubscribe(session *Session, topic string) {
+	if session == nil {
+		return
+	}
 	client := *session.Client
 	client.Unsubscribe(topic)
 }