diff --git a/tests/ModelContextProtocol.Tests/Server/McpServerTests.cs b/tests/ModelContextProtocol.Tests/Server/McpServerTests.cs
index 15dc5c98b..a5524c8aa 100644
--- a/tests/ModelContextProtocol.Tests/Server/McpServerTests.cs
+++ b/tests/ModelContextProtocol.Tests/Server/McpServerTests.cs
@@ -89,10 +89,12 @@ public async Task StartAsync_Should_Throw_InvalidOperationException_If_Already_I
     {
         // Arrange
         await using var server = McpServerFactory.Create(_serverTransport.Object, _options, _loggerFactory.Object, _serviceProvider);
-        server.GetType().GetField("_isInitializing", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)?.SetValue(server, true);
+        var task = server.StartAsync(TestContext.Current.CancellationToken);
 
         // Act & Assert
         await Assert.ThrowsAsync<InvalidOperationException>(() => server.StartAsync(TestContext.Current.CancellationToken));
+
+        await task;
     }
 
     [Fact]
diff --git a/tests/ModelContextProtocol.Tests/Transport/SseClientTransportTests.cs b/tests/ModelContextProtocol.Tests/Transport/SseClientTransportTests.cs
index 53d41cc1f..b91090355 100644
--- a/tests/ModelContextProtocol.Tests/Transport/SseClientTransportTests.cs
+++ b/tests/ModelContextProtocol.Tests/Transport/SseClientTransportTests.cs
@@ -110,48 +110,44 @@ public async Task ConnectAsync_Throws_If_Already_Connected()
         using var mockHttpHandler = new MockHttpHandler();
         using var httpClient = new HttpClient(mockHttpHandler);
         await using var transport = new SseClientTransport(_transportOptions, _serverConfig, httpClient, NullLoggerFactory.Instance);
-        using var mreConnected = new ManualResetEventSlim(false);
-        using var mreDone = new ManualResetEventSlim(false);
+        var tcsConnected = new TaskCompletionSource();
+        var tcsDone = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
         var callIndex = 0;
 
-        mockHttpHandler.RequestHandler = (request) =>
+        mockHttpHandler.RequestHandler = async (request) =>
         {
             switch (callIndex++)
             {
                 case 0:
-                    return Task.FromResult(new HttpResponseMessage
+                    return new HttpResponseMessage
                     {
                         StatusCode = HttpStatusCode.OK,
                         Content = new StringContent("event: endpoint\r\ndata: http://localhost\r\n\r\n")
-                    });
+                    };
                 case 1:
-                    mreConnected.Set();
-                    mreDone.Wait();
-                    return Task.FromResult(new HttpResponseMessage
+                    tcsConnected.SetResult();
+                    await tcsDone.Task;
+                    return new HttpResponseMessage
                     {
                         StatusCode = HttpStatusCode.OK,
                         Content = new StringContent("")
-                    });
+                    };
                 default:
-                    return Task.FromResult(new HttpResponseMessage
+                    return new HttpResponseMessage
                     {
                         StatusCode = HttpStatusCode.OK,
                         Content = new StringContent("")
-                    });
+                    };
             }
         };
 
-        var task = Task.Run(async () =>
-        {
-            await transport.ConnectAsync(TestContext.Current.CancellationToken);
-        }, TestContext.Current.CancellationToken);
-
-        mreConnected.Wait(TestContext.Current.CancellationToken);
+        var task = transport.ConnectAsync(TestContext.Current.CancellationToken);
+        await tcsConnected.Task;
         Assert.True(transport.IsConnected);
         var action = async () => await transport.ConnectAsync();
         var exception = await Assert.ThrowsAsync<McpTransportException>(action);
         Assert.Equal("Transport is already connected", exception.Message);
-        mreDone.Set();
+        tcsDone.SetResult();
         await transport.CloseAsync();
         await task;
     }