diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs
index bc94e7f5..fe57552f 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs
@@ -227,7 +227,7 @@ namespace MQTTnet.Server
             }
 
             var interceptorContext = new MqttApplicationMessageInterceptorContext(
-                senderClientSession.ClientId,
+                senderClientSession?.ClientId,
                 applicationMessage);
 
             interceptor(interceptorContext);