diff --git a/Source/MQTTnet/Client/MqttClient.cs b/Source/MQTTnet/Client/MqttClient.cs
index 0a408d08..05330b5d 100644
--- a/Source/MQTTnet/Client/MqttClient.cs
+++ b/Source/MQTTnet/Client/MqttClient.cs
@@ -29,7 +29,7 @@ namespace MQTTnet.Client
         internal Task _keepAliveMessageSenderTask;
         private IMqttChannelAdapter _adapter;
         private bool _cleanDisconnectInitiated;
-        private TaskCompletionSource<bool> _disconnectReason;
+        private int _disconnectGate;
 
         public MqttClient(IMqttClientAdapterFactory channelFactory, IMqttNetLogger logger)
         {
@@ -59,7 +59,7 @@ namespace MQTTnet.Client
                 _packetDispatcher.Reset();
 
                 _cancellationTokenSource = new CancellationTokenSource();
-                _disconnectReason = new TaskCompletionSource<bool>();
+                _disconnectGate = 0;
                 _adapter = _adapterFactory.CreateClientAdapter(options, _logger);
 
                 _logger.Verbose($"Trying to connect with server ({_options.ChannelOptions}).");
@@ -88,7 +88,7 @@ namespace MQTTnet.Client
             {
                 _logger.Error(exception, "Error while connecting with server.");
 
-                if (_disconnectReason.TrySetException(exception))
+                if (!DisconnectIsPending())
                 {
                     await DisconnectInternalAsync(null, exception).ConfigureAwait(false);
                 }
@@ -110,7 +110,7 @@ namespace MQTTnet.Client
             }
             finally
             {
-                if (_disconnectReason.TrySetCanceled())
+                if (!DisconnectIsPending())
                 {
                     await DisconnectInternalAsync(null, null).ConfigureAwait(false);
                 }
@@ -361,7 +361,7 @@ namespace MQTTnet.Client
                     _logger.Error(exception, "Unhandled exception while sending/receiving keep alive packets.");
                 }
 
-                if (_disconnectReason.TrySetException(exception))
+                if (!DisconnectIsPending())
                 {
                     await DisconnectInternalAsync(_keepAliveMessageSenderTask, exception).ConfigureAwait(false);
                 }
@@ -410,7 +410,7 @@ namespace MQTTnet.Client
 
                 _packetDispatcher.Dispatch(exception);
 
-                if (_disconnectReason.TrySetException(exception))
+                if (!DisconnectIsPending())
                 {
                     await DisconnectInternalAsync(_packetReceiverTask, exception).ConfigureAwait(false);
                 }
@@ -545,5 +545,10 @@ namespace MQTTnet.Client
             {
             }
         }
+
+        private bool DisconnectIsPending()
+        {
+            return Interlocked.CompareExchange(ref _disconnectGate, 1, 0) != 0;
+        }
     }
 }
\ No newline at end of file
diff --git a/Tests/MQTTnet.Core.Tests/MqttServerTests.cs b/Tests/MQTTnet.Core.Tests/MqttServerTests.cs
index e4e5b3b9..0404ccc0 100644
--- a/Tests/MQTTnet.Core.Tests/MqttServerTests.cs
+++ b/Tests/MQTTnet.Core.Tests/MqttServerTests.cs
@@ -669,25 +669,24 @@ namespace MQTTnet.Core.Tests
             MqttQualityOfServiceLevel filterQualityOfServiceLevel,
             int expectedReceivedMessagesCount)
         {
-            var serverAdapter = new TestMqttServerAdapter();
-            var s = new MqttFactory().CreateMqttServer(new[] { serverAdapter }, new MqttNetLogger());
+            var s = new MqttFactory().CreateMqttServer();
 
             var receivedMessagesCount = 0;
             try
             {
                 await s.StartAsync(new MqttServerOptions());
 
-                var c1 = await serverAdapter.ConnectTestClient("c1");
-                var c2 = await serverAdapter.ConnectTestClient("c2");
-
+                var c1 = new MqttFactory().CreateMqttClient();
                 c1.ApplicationMessageReceived += (_, __) => receivedMessagesCount++;
-
+                await c1.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("localhost").Build());
                 await c1.SubscribeAsync(new TopicFilterBuilder().WithTopic(topicFilter).WithQualityOfServiceLevel(filterQualityOfServiceLevel).Build());
+
+                var c2 = new MqttFactory().CreateMqttClient();
+                await c2.ConnectAsync(new MqttClientOptionsBuilder().WithTcpServer("localhost").Build());
                 await c2.PublishAsync(builder => builder.WithTopic(topic).WithPayload(new byte[0]).WithQualityOfServiceLevel(qualityOfServiceLevel));
 
                 await Task.Delay(500);
                 await c1.UnsubscribeAsync(topicFilter);
-
                 await Task.Delay(500);
             }
             finally