diff --git a/packages/services/notification-service/src/application/services/offline-push.service.ts b/packages/services/notification-service/src/application/services/offline-push.service.ts
index 8219fbc..fa287c5 100644
--- a/packages/services/notification-service/src/application/services/offline-push.service.ts
+++ b/packages/services/notification-service/src/application/services/offline-push.service.ts
@@ -35,7 +35,7 @@ export interface NotificationForPush {
 @Injectable()
 export class OfflinePushService implements OnModuleInit {
   private readonly logger = new Logger(OfflinePushService.name);
-  private readonly providers: Map<string, PushProvider>;
+  private readonly providers: Map<string, PushProvider> = new Map();
 
   constructor(
     private readonly tokenRepo: DevicePushTokenRepository,
@@ -45,13 +45,11 @@ export class OfflinePushService implements OnModuleInit {
     private readonly oppo: OppoProvider,
     private readonly vivo: VivoProvider,
   ) {
-    this.providers = new Map([
-      ['FCM',  fcm],
-      ['HMS',  hms],
-      ['MI',   xiaomi],
-      ['OPPO', oppo],
-      ['VIVO', vivo],
-    ]);
+    this.providers.set('FCM',  fcm);
+    this.providers.set('HMS',  hms);
+    this.providers.set('MI',   xiaomi);
+    this.providers.set('OPPO', oppo);
+    this.providers.set('VIVO', vivo);
   }
 
   onModuleInit(): void {