diff --git a/src/apps/mqtt/mqtt.c b/src/apps/mqtt/mqtt.c
index 8e5c206a..0da1a405 100644
--- a/src/apps/mqtt/mqtt.c
+++ b/src/apps/mqtt/mqtt.c
@@ -770,7 +770,9 @@ mqtt_message_received(mqtt_client_t *client, u8_t fixed_hdr_len, u16_t length, u
         LWIP_DEBUGF(MQTT_DEBUG_WARN,( "mqtt_message_received: Received short packet (payload)\n"));
         goto out_disconnect;
       }
-      client->data_cb(client->inpub_arg, var_hdr_payload + payload_offset, payload_length, remaining_length == 0 ? MQTT_DATA_FLAG_LAST : 0);
+      if (client->data_cb != NULL) {
+        client->data_cb(client->inpub_arg, var_hdr_payload + payload_offset, payload_length, remaining_length == 0 ? MQTT_DATA_FLAG_LAST : 0);
+      }
       /* Reply if QoS > 0 */
       if (remaining_length == 0 && qos > 0) {
         /* Send PUBACK for QoS 1 or PUBREC for QoS 2 */