diff --git a/OpenAuth.WebApi/Startup.cs b/OpenAuth.WebApi/Startup.cs
index 12cb679..e7e6440 100644
--- a/OpenAuth.WebApi/Startup.cs
+++ b/OpenAuth.WebApi/Startup.cs
@@ -46,7 +46,7 @@ namespace OpenAuth.WebApi
         public void ConfigureServices(IServiceCollection services)
         {
             services.AddHttpContextAccessor();
-            services.AddSingleton(_ => new MqttClientManager());
+            services.AddSingleton<MqttClientManager>();
             // minio client 
             services.AddSingleton(_ => new MinioService());