diff --git a/lib/tools/mqtt_core.dart b/lib/tools/mqtt_core.dart
index c876d0c..b987b26 100644
--- a/lib/tools/mqtt_core.dart
+++ b/lib/tools/mqtt_core.dart
@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:math';
 
+import 'package:flutter/foundation.dart';
 import 'package:isar/isar.dart';
 import 'package:mqtt_client/mqtt_client.dart';
 import 'package:mqtt_client/mqtt_server_client.dart';