diff --git a/MQTTSNGateway/src/MQTTGWPublishHandler.cpp b/MQTTSNGateway/src/MQTTGWPublishHandler.cpp
index e73a7cc..dfa8928 100644
--- a/MQTTSNGateway/src/MQTTGWPublishHandler.cpp
+++ b/MQTTSNGateway/src/MQTTGWPublishHandler.cpp
@@ -127,8 +127,15 @@ void MQTTGWPublishHandler::handlePublish(Client* client, MQTTGWPacket* packet)
 
             /* add the Topic and get a TopicId */
             topic = client->getTopics()->add(&topicId);
-            id = topic->getTopicId();
+            if (topic == nullptr)
+            {
+                WRITELOG("%sMQTTGWPublishHandler Can't Add a Topic. MAX_TOPIC_PAR_CLIENT is exceeded.%s\n",
+                        ERRMSG_HEADER, ERRMSG_FOOTER);
+                delete snPacket;
+                return;
+            }
 
+            id = topic->getTopicId();
             if (id > 0)
             {
                 /* create REGISTER */
diff --git a/MQTTSNGateway/src/MQTTSNGWSubscribeHandler.cpp b/MQTTSNGateway/src/MQTTSNGWSubscribeHandler.cpp
index 906e3fa..2b4f0a6 100644
--- a/MQTTSNGateway/src/MQTTSNGWSubscribeHandler.cpp
+++ b/MQTTSNGateway/src/MQTTSNGWSubscribeHandler.cpp
@@ -68,6 +68,12 @@ MQTTGWPacket* MQTTSNSubscribeHandler::handleSubscribe(Client* client,
             {
                 topic = client->getTopics()->add(topic->getTopicName()->c_str(),
                         topic->getTopicId());
+                if (topic == nullptr)
+                {
+                	WRITELOG("%s Client(%s) can't add the Topic.%s\n",
+                	        ERRMSG_HEADER, client->getClientId(), ERRMSG_FOOTER);
+                    goto RespExit;
+                }
             }
             else
             {
@@ -90,7 +96,7 @@ MQTTGWPacket* MQTTSNSubscribeHandler::handleSubscribe(Client* client,
             {
                 WRITELOG("%s Client(%s) can't add the Topic.%s\n",
                         ERRMSG_HEADER, client->getClientId(), ERRMSG_FOOTER);
-                return nullptr;
+                goto RespExit;
             }
         }
         topicId = topic->getTopicId();