diff --git a/Capnp.Net.Runtime.Tests/Dtbdct.cs b/Capnp.Net.Runtime.Tests/Dtbdct.cs
index fa48434..57ae39c 100644
--- a/Capnp.Net.Runtime.Tests/Dtbdct.cs
+++ b/Capnp.Net.Runtime.Tests/Dtbdct.cs
@@ -158,5 +158,23 @@ namespace Capnp.Net.Runtime.Tests
         {
             NewDtbdctTestbed().RunTest(Testsuite.ImportReceiverCanceled);
         }
+
+        [TestMethod]
+        public void ButNoTailCall()
+        {
+            NewDtbdctTestbed().RunTest(Testsuite.ButNoTailCall);
+        }
+
+        [TestMethod]
+        public void SecondIsTailCall()
+        {
+            NewDtbdctTestbed().RunTest(Testsuite.SecondIsTailCall);
+        }
+
+        [TestMethod]
+        public void ReexportSenderPromise()
+        {
+            NewDtbdctTestbed().RunTest(Testsuite.ReexportSenderPromise);
+        }
     }
 }
diff --git a/Capnp.Net.Runtime.Tests/Mock/TestCapImplementations.cs b/Capnp.Net.Runtime.Tests/Mock/TestCapImplementations.cs
index e26b84d..795d451 100644
--- a/Capnp.Net.Runtime.Tests/Mock/TestCapImplementations.cs
+++ b/Capnp.Net.Runtime.Tests/Mock/TestCapImplementations.cs
@@ -681,6 +681,72 @@ namespace Capnp.Net.Runtime.Tests.GenImpls
             }
         }
     }
+
+    class TestTailCallerImpl3 : ITestTailCaller
+    {
+        public TestTailCallerImpl3()
+        {
+        }
+
+        public void Dispose()
+        {
+        }
+
+        public Task<TestTailCallee.TailResult> Foo(int i, ITestTailCallee callee, CancellationToken cancellationToken_)
+        {
+            using (callee)
+            {
+                var task1 = callee.Foo(i, "from TestTailCaller 1", cancellationToken_);
+
+                async void FinishTask()
+                {
+                    var r = await task1;
+                    r.C.Dispose();
+                }
+
+                FinishTask();
+
+                var task2 = callee.Foo(i, "from TestTailCaller 2", cancellationToken_);
+
+                async void AssertIsTailCall()
+                {
+                    try
+                    {
+                        await task2;
+                        Assert.Fail("Not a tail call");
+                    }
+                    catch (TailCallNoDataException)
+                    {
+                    }
+                }
+
+                AssertIsTailCall();
+
+                return task2;
+            }
+        }
+    }
+
+    class TestTailCallerImpl4 : ITestTailCaller
+    {
+        public TestTailCallerImpl4()
+        {
+        }
+
+        public void Dispose()
+        {
+        }
+
+        public async Task<TestTailCallee.TailResult> Foo(int i, ITestTailCallee callee, CancellationToken cancellationToken_)
+        {
+            await Task.Yield();
+
+            using (callee)
+            {
+                return await callee.Foo(i, "from TestTailCaller", cancellationToken_);
+            }
+        }
+    }
     #endregion TestTailCaller
 
     #region TestTailCallee
@@ -993,7 +1059,7 @@ namespace Capnp.Net.Runtime.Tests.GenImpls
         {
             if (_echoCounter++ < 20)
             {
-                return Task.FromResult<ITestCallOrder>(((Proxy)cap).Cast<ITestMoreStuff>(true).Echo(cap).Eager());
+                return Task.FromResult(((Proxy)cap).Cast<ITestMoreStuff>(false).Echo(cap).Eager());
             }
             else
             {
@@ -1056,6 +1122,192 @@ namespace Capnp.Net.Runtime.Tests.GenImpls
         }
     }
 
+    class TestMoreStuffImpl4 : ITestMoreStuff, ITestCallOrder
+    {
+        readonly TaskCompletionSource<ITestInterface> _heldCap = new TaskCompletionSource<ITestInterface>();
+
+        public Task<string> CallFoo(ITestInterface cap, CancellationToken cancellationToken_ = default)
+        {
+            using (cap)
+            {
+                return cap.Foo(123, true);
+            }
+        }
+
+        public Task<string> CallFooWhenResolved(ITestInterface Cap, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<string> CallHeld(CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public async void Dispose()
+        {
+            using (var cap = await _heldCap.Task)
+            {
+            }
+        }
+
+        public Task<ITestCallOrder> Echo(ITestCallOrder cap, CancellationToken cancellationToken_ = default)
+        {
+            using (var target = ((Proxy)cap).Cast<ITestMoreStuff>(false))
+            {
+                return Task.FromResult(target.Echo(cap).Eager());
+            }
+        }
+
+        public Task ExpectCancel(ITestInterface Cap, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        uint _counter;
+
+        public Task<uint> GetCallSequence(uint expected, CancellationToken cancellationToken_ = default)
+        {
+            Assert.AreEqual(_counter, expected);
+            return Task.FromResult(_counter++);
+        }
+
+        public Task<string> GetEnormousString(CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<ITestHandle> GetHandle(CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<ITestInterface> GetHeld(CancellationToken cancellationToken_ = default)
+        {
+            return Task.FromResult(_heldCap.Task.Eager(true));
+        }
+
+        public Task<ITestMoreStuff> GetNull(CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task Hold(ITestInterface Cap, CancellationToken cancellationToken_ = default)
+        {
+            _heldCap.SetResult(Cap);
+            return Task.CompletedTask;
+        }
+
+        public Task<(string, string)> MethodWithDefaults(string A, uint B, string C, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task MethodWithNullDefault(string A, ITestInterface B, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<ITestInterface> NeverReturn(ITestInterface Cap, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    class TestMoreStuffImpl5 : ITestMoreStuff, ITestCallOrder
+    {
+        readonly TaskCompletionSource<ITestInterface> _heldCap = new TaskCompletionSource<ITestInterface>();
+
+        public Task<string> CallFoo(ITestInterface cap, CancellationToken cancellationToken_ = default)
+        {
+            using (cap)
+            {
+                return cap.Foo(123, true);
+            }
+        }
+
+        public Task<string> CallFooWhenResolved(ITestInterface Cap, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<string> CallHeld(CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public async void Dispose()
+        {
+            using (var cap = await _heldCap.Task)
+            {
+            }
+        }
+
+        TaskCompletionSource<int> _echoEnabled = new TaskCompletionSource<int>();
+
+        public void EnableEcho() => _echoEnabled.SetResult(0);
+
+        public async Task<ITestCallOrder> Echo(ITestCallOrder cap, CancellationToken cancellationToken_ = default)
+        {
+            await _echoEnabled.Task;
+            return cap;
+        }
+
+        public Task ExpectCancel(ITestInterface Cap, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        uint _counter;
+
+        public Task<uint> GetCallSequence(uint expected, CancellationToken cancellationToken_ = default)
+        {
+            Assert.AreEqual(_counter, expected);
+            return Task.FromResult(_counter++);
+        }
+
+        public Task<string> GetEnormousString(CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<ITestHandle> GetHandle(CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<ITestInterface> GetHeld(CancellationToken cancellationToken_ = default)
+        {
+            return Task.FromResult(_heldCap.Task.Eager(true));
+        }
+
+        public Task<ITestMoreStuff> GetNull(CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task Hold(ITestInterface Cap, CancellationToken cancellationToken_ = default)
+        {
+            _heldCap.SetResult(Cap);
+            return Task.CompletedTask;
+        }
+
+        public Task<(string, string)> MethodWithDefaults(string A, uint B, string C, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task MethodWithNullDefault(string A, ITestInterface B, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task<ITestInterface> NeverReturn(ITestInterface Cap, CancellationToken cancellationToken_ = default)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
     #endregion TestMoreStuff
 
     #region TestHandle
diff --git a/Capnp.Net.Runtime.Tests/TcpRpcAdvancedStuff.cs b/Capnp.Net.Runtime.Tests/TcpRpcAdvancedStuff.cs
index f9483bf..6d41fc9 100644
--- a/Capnp.Net.Runtime.Tests/TcpRpcAdvancedStuff.cs
+++ b/Capnp.Net.Runtime.Tests/TcpRpcAdvancedStuff.cs
@@ -261,20 +261,29 @@ namespace Capnp.Net.Runtime.Tests
                     {
                         var echoTask = main.Echo(Proxy.Share<ITestCallOrder>(main));
                         Assert.IsTrue(echoTask.Wait(MediumNonDbgTimeout));
-                        var echo = echoTask.Result;
-                        var list = new Task<uint>[1000];
-                        for (uint i = 0; i < list.Length; i++)
+                        using (var echo = echoTask.Result)
                         {
-                            list[i] = echo.GetCallSequence(i);
-                        }
-                        Assert.IsTrue(Task.WaitAll(list, MediumNonDbgTimeout));
-                        for (uint i = 0; i < list.Length; i++)
-                        {
-                            Assert.AreEqual(i, list[i].Result);
+                            var list = new Task<uint>[1000];
+                            for (uint i = 0; i < list.Length; i++)
+                            {
+                                list[i] = echo.GetCallSequence(i);
+                            }
+                            Assert.IsTrue(Task.WaitAll(list, MediumNonDbgTimeout));
+                            for (uint i = 0; i < list.Length; i++)
+                            {
+                                Assert.AreEqual(i, list[i].Result);
+                            }
                         }
                     }
                 }
             }
         }
+
+
+        [TestMethod]
+        public void NoTailCallMt()
+        {
+            NewLocalhostTcpTestbed().RunTest(Testsuite.NoTailCallMt);
+        }
     }
 }
diff --git a/Capnp.Net.Runtime.Tests/TcpRpcInterop.cs b/Capnp.Net.Runtime.Tests/TcpRpcInterop.cs
index e093a27..5886456 100644
--- a/Capnp.Net.Runtime.Tests/TcpRpcInterop.cs
+++ b/Capnp.Net.Runtime.Tests/TcpRpcInterop.cs
@@ -415,20 +415,22 @@ namespace Capnp.Net.Runtime.Tests
                         var callee = new TestTailCalleeImpl(calleeCallCount);
 
                         var promise = main.Foo(456, callee, default);
-                        var dependentCall0 = promise.C().GetCallSequence(0, default);
+                        using (var c = promise.C())
+                        {
+                            var dependentCall0 = c.GetCallSequence(0, default);
 
-                        Assert.IsTrue(promise.Wait(MediumNonDbgTimeout));
-                        Assert.AreEqual(456u, promise.Result.I);
-                        Assert.AreEqual("from TestTailCaller", promise.Result.T);
+                            Assert.IsTrue(promise.Wait(MediumNonDbgTimeout));
+                            Assert.AreEqual(456u, promise.Result.I);
+                            Assert.AreEqual("from TestTailCaller", promise.Result.T);
 
-                        var dependentCall1 = promise.C().GetCallSequence(0, default);
-                        var dependentCall2 = promise.C().GetCallSequence(0, default);
-
-                        AssertOutput(stdout, "foo");
-                        Assert.IsTrue(dependentCall0.Wait(MediumNonDbgTimeout));
-                        Assert.IsTrue(dependentCall1.Wait(MediumNonDbgTimeout));
-                        Assert.IsTrue(dependentCall2.Wait(MediumNonDbgTimeout));
+                            var dependentCall1 = c.GetCallSequence(0, default);
+                            var dependentCall2 = c.GetCallSequence(0, default);
 
+                            AssertOutput(stdout, "foo");
+                            Assert.IsTrue(dependentCall0.Wait(MediumNonDbgTimeout));
+                            Assert.IsTrue(dependentCall1.Wait(MediumNonDbgTimeout));
+                            Assert.IsTrue(dependentCall2.Wait(MediumNonDbgTimeout));
+                        }
                         Assert.AreEqual(1, calleeCallCount.CallCount);
                     }
                 }
@@ -523,28 +525,30 @@ namespace Capnp.Net.Runtime.Tests
                     using (var main = client.GetMain<ITestMoreStuff>())
                     {
                         var tcs = new TaskCompletionSource<ITestInterface>();
-                        var eager = tcs.Task.Eager(true);
+                        using (var eager = tcs.Task.Eager(true))
+                        {
+                            var request = main.CallFoo(Proxy.Share(eager), default);
+                            AssertOutput(stdout, "callFoo");
+                            var request2 = main.CallFooWhenResolved(Proxy.Share(eager), default);
+                            AssertOutput(stdout, "callFooWhenResolved");
 
-                        var request = main.CallFoo(eager, default);
-                        AssertOutput(stdout, "callFoo");
-                        var request2 = main.CallFooWhenResolved(eager, default);
-                        AssertOutput(stdout, "callFooWhenResolved");
+                            var gcs = main.GetCallSequence(0, default);
+                            AssertOutput(stdout, "getCallSequence");
+                            Assert.IsTrue(gcs.Wait(MediumNonDbgTimeout));
+                            Assert.AreEqual(2u, gcs.Result);
 
-                        var gcs = main.GetCallSequence(0, default);
-                        AssertOutput(stdout, "getCallSequence");
-                        Assert.IsTrue(gcs.Wait(MediumNonDbgTimeout));
-                        Assert.AreEqual(2u, gcs.Result);
+                            var chainedCallCount = new Counters();
+                            var tiimpl = new TestInterfaceImpl(chainedCallCount);
+                            tcs.SetResult(tiimpl);
 
-                        var chainedCallCount = new Counters();
-                        var tiimpl = new TestInterfaceImpl(chainedCallCount);
-                        tcs.SetResult(tiimpl);
+                            Assert.IsTrue(request.Wait(MediumNonDbgTimeout));
+                            Assert.IsTrue(request2.Wait(MediumNonDbgTimeout));
 
-                        Assert.IsTrue(request.Wait(MediumNonDbgTimeout));
-                        Assert.IsTrue(request2.Wait(MediumNonDbgTimeout));
+                            Assert.AreEqual("bar", request.Result);
+                            Assert.AreEqual("bar", request2.Result);
+                            Assert.AreEqual(2, chainedCallCount.CallCount);
 
-                        Assert.AreEqual("bar", request.Result);
-                        Assert.AreEqual("bar", request2.Result);
-                        Assert.AreEqual(2, chainedCallCount.CallCount);
+                        }
 
                         AssertOutput(stdout, "fin");
                         AssertOutput(stdout, "fin");
diff --git a/Capnp.Net.Runtime.Tests/Testsuite.cs b/Capnp.Net.Runtime.Tests/Testsuite.cs
index 443beea..c64c0be 100644
--- a/Capnp.Net.Runtime.Tests/Testsuite.cs
+++ b/Capnp.Net.Runtime.Tests/Testsuite.cs
@@ -749,5 +749,74 @@ namespace Capnp.Net.Runtime.Tests
                 Assert.IsTrue(foo.IsCanceled);
             }
         }
+
+        public static void ButNoTailCall(ITestbed testbed)
+        {
+            var impl = new TestMoreStuffImpl4();
+            using (var main = testbed.ConnectMain<ITestMoreStuff>(impl))
+            {
+                var peer = new TestMoreStuffImpl5();
+                var heldTask = main.Echo(peer);
+
+                testbed.MustComplete(heldTask);
+
+                var r = heldTask.Result as IResolvingCapability;
+
+                peer.EnableEcho();
+
+                testbed.MustComplete(r.WhenResolved);
+
+                heldTask.Result.Dispose();
+            }
+        }
+
+        public static void SecondIsTailCall(ITestbed testbed)
+        {
+            var impl = new TestTailCallerImpl3();
+            using (var main = testbed.ConnectMain<ITestTailCaller>(impl))
+            {
+                var callee = new TestTailCalleeImpl(new Counters());
+                var task = main.Foo(123, callee);
+                testbed.MustComplete(task);
+                Assert.AreEqual("from TestTailCaller 2", task.Result.T);
+            }
+        }
+
+        public static void NoTailCallMt(ITestbed testbed)
+        {
+            var impl = new TestTailCallerImpl4();
+            using (var main = testbed.ConnectMain<ITestTailCaller>(impl))
+            using (var callee = Proxy.Share<ITestTailCallee>(new TestTailCalleeImpl(new Counters())))
+            {
+                var tasks = ParallelEnumerable
+                    .Range(0, 1000)
+                    .Select(async i =>
+                    {
+                        var r = await main.Foo(i, Proxy.Share(callee));
+                        Assert.AreEqual((uint)i, r.I);
+                    })
+                    .ToArray();
+
+                testbed.MustComplete(tasks);
+                Assert.IsFalse(tasks.Any(t => t.IsCanceled || t.IsFaulted));
+            }
+        }
+
+        public static void ReexportSenderPromise(ITestbed testbed)
+        {
+            var impl = new TestTailCallerImpl(new Counters());
+            using (var main = testbed.ConnectMain<ITestTailCaller>(impl))
+            {
+                var tcs = new TaskCompletionSource<ITestTailCallee>();
+                using (var promise = Proxy.Share(tcs.Task.Eager(true)))
+                {
+                    var task1 = main.Foo(1, Proxy.Share(promise));
+                    var task2 = main.Foo(2, Proxy.Share(promise));
+                    var callee = new TestTailCalleeImpl(new Counters());
+                    tcs.SetResult(callee);
+                    testbed.MustComplete(task1, task2);
+                }
+            }
+        }
     }
 }
diff --git a/Capnp.Net.Runtime.Tests/Util/TestBase.cs b/Capnp.Net.Runtime.Tests/Util/TestBase.cs
index 000b810..e40b7a1 100644
--- a/Capnp.Net.Runtime.Tests/Util/TestBase.cs
+++ b/Capnp.Net.Runtime.Tests/Util/TestBase.cs
@@ -242,11 +242,16 @@ namespace Capnp.Net.Runtime.Tests
             {
                 (_server, _client) = SetupClientServerPair();
                 _client.WhenConnected.Wait(MediumNonDbgTimeout);
+                Assert.IsTrue(SpinWait.SpinUntil(() => _server.ConnectionCount > 0, MediumNonDbgTimeout));
+                var conn = _server.Connections[0];
 
                 using (_server)
                 using (_client)
                 {
                     action(this);
+
+                    Assert.IsTrue(SpinWait.SpinUntil(() => _client.SendCount == conn.RecvCount, MediumNonDbgTimeout));
+                    Assert.IsTrue(SpinWait.SpinUntil(() => conn.SendCount == _client.RecvCount, MediumNonDbgTimeout));
                 }
             }
 
diff --git a/Capnp.Net.Runtime/Capnp.Net.Runtime.csproj b/Capnp.Net.Runtime/Capnp.Net.Runtime.csproj
index b7675b9..6f81750 100644
--- a/Capnp.Net.Runtime/Capnp.Net.Runtime.csproj
+++ b/Capnp.Net.Runtime/Capnp.Net.Runtime.csproj
@@ -29,7 +29,7 @@
   </PropertyGroup>
 
   <PropertyGroup>
-    <DefineConstants></DefineConstants>
+    <DefineConstants>DebugFinalizers</DefineConstants>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|netstandard2.0|AnyCPU'">
diff --git a/Capnp.Net.Runtime/Rpc/Impatient.cs b/Capnp.Net.Runtime/Rpc/Impatient.cs
index d969ddc..0f4685c 100644
--- a/Capnp.Net.Runtime/Rpc/Impatient.cs
+++ b/Capnp.Net.Runtime/Rpc/Impatient.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
@@ -11,7 +12,7 @@ namespace Capnp.Rpc
     public static class Impatient
     {
         static readonly ConditionalWeakTable<Task, IPromisedAnswer> _taskTable = new ConditionalWeakTable<Task, IPromisedAnswer>();
-        static readonly ThreadLocal<IRpcEndpoint?> _askingEndpoint = new ThreadLocal<IRpcEndpoint?>();
+        static readonly ThreadLocal<Stack<IRpcEndpoint>> _askingEndpoint = new ThreadLocal<Stack<IRpcEndpoint>>(() => new Stack<IRpcEndpoint>());
 
         /// <summary>
         /// Attaches a continuation to the given promise and registers the resulting task for pipelining.
@@ -171,8 +172,17 @@ namespace Capnp.Rpc
 
         internal static IRpcEndpoint? AskingEndpoint
         {
-            get => _askingEndpoint.Value;
-            set { _askingEndpoint.Value = value; }
+            get => _askingEndpoint.Value!.Count > 0 ? _askingEndpoint.Value.Peek() : null;
+        }
+
+        internal static void PushAskingEndpoint(IRpcEndpoint endpoint)
+        {
+            _askingEndpoint.Value!.Push(endpoint);
+        }
+
+        internal static void PopAskingEndpoint()
+        {
+            _askingEndpoint.Value!.Pop();
         }
 
         /// <summary>
diff --git a/Capnp.Net.Runtime/Rpc/PendingQuestion.cs b/Capnp.Net.Runtime/Rpc/PendingQuestion.cs
index 5884656..5d6aa50 100644
--- a/Capnp.Net.Runtime/Rpc/PendingQuestion.cs
+++ b/Capnp.Net.Runtime/Rpc/PendingQuestion.cs
@@ -66,14 +66,6 @@ namespace Capnp.Rpc
             _inParams = inParams;
             StateFlags = inParams == null ? State.Sent : State.None;
 
-            if (inParams != null)
-            {
-                foreach (var cap in inParams.Caps!)
-                {
-                    cap.AddRef();
-                }
-            }
-
             if (target != null)
             {
                 target.AddRef();
@@ -282,22 +274,6 @@ namespace Capnp.Rpc
             return new RemoteAnswerCapability(this, access, proxyTask);
         }
 
-        static void ReleaseCaps(ConsumedCapability? target, SerializerState? inParams)
-        {
-            if (inParams != null)
-            {
-                foreach (var cap in inParams.Caps!)
-                {
-                    cap.Release();
-                }
-            }
-
-            if (target != null)
-            {
-                target.Release();
-            }
-        }
-
         static void ReleaseOutCaps(DeserializerState outParams)
         {
             foreach (var cap in outParams.Caps!)
@@ -327,8 +303,8 @@ namespace Capnp.Rpc
             Debug.Assert(msg.Call!.Target.which != MessageTarget.WHICH.undefined);
             var call = msg.Call;
             call.QuestionId = QuestionId;
-            call.SendResultsTo.which = IsTailCall ? 
-                Call.sendResultsTo.WHICH.Yourself : 
+            call.SendResultsTo.which = IsTailCall ?
+                Call.sendResultsTo.WHICH.Yourself :
                 Call.sendResultsTo.WHICH.Caller;
 
             try
@@ -341,7 +317,7 @@ namespace Capnp.Rpc
                 OnException(exception);
             }
 
-            ReleaseCaps(target, inParams);
+            target?.Release();
         }
 
         /// <summary>
diff --git a/Capnp.Net.Runtime/Rpc/Proxy.cs b/Capnp.Net.Runtime/Rpc/Proxy.cs
index 419826e..bcfa0be 100644
--- a/Capnp.Net.Runtime/Rpc/Proxy.cs
+++ b/Capnp.Net.Runtime/Rpc/Proxy.cs
@@ -1,5 +1,6 @@
 using Microsoft.Extensions.Logging;
 using System;
+using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -25,10 +26,6 @@ namespace Capnp.Rpc
                 return BareProxy.FromImpl(obj).Cast<T>(true);
         }
 
-#if DebugFinalizers
-        ILogger Logger { get; } = Logging.CreateLogger<Proxy>();
-#endif
-
         bool _disposedValue = false;
 
         /// <summary>
@@ -56,15 +53,23 @@ namespace Capnp.Rpc
                 return CapabilityReflection.CreateProxy<T>(ConsumedCap) as T;
         }
 
+        ConsumedCapability? _consumedCap;
+
         /// <summary>
         /// Underlying low-level capability
         /// </summary>
-        protected internal ConsumedCapability? ConsumedCap { get; private set; }
+        protected internal ConsumedCapability? ConsumedCap => _disposedValue ?
+            throw new ObjectDisposedException(nameof(Proxy)) : _consumedCap;
 
         /// <summary>
         /// Whether is this a broken capability.
         /// </summary>
-        public bool IsNull => ConsumedCap == null;
+        public bool IsNull => _consumedCap == null;
+
+        /// <summary>
+        /// Whether <see cref="Dispose()"/> was called on this Proxy.
+        /// </summary>
+        public bool IsDisposed => _disposedValue;
 
         static async void DisposeCtrWhenReturned(CancellationTokenRegistration ctr, IPromisedAnswer answer)
         {
@@ -134,12 +139,12 @@ namespace Capnp.Rpc
             if (cap == null)
                 return;
 
-            ConsumedCap = cap;
+            _consumedCap = cap;
             cap.AddRef();
 
 #if DebugFinalizers
-            if (ConsumedCap != null)
-                ConsumedCap.OwningProxy = this;
+            if (_consumedCap != null)
+                _consumedCap.OwningProxy = this;
 #endif
         }
 
@@ -166,14 +171,14 @@ namespace Capnp.Rpc
             {
                 if (disposing)
                 {
-                    ConsumedCap?.Release();
+                    _consumedCap?.Release();
                 }
                 else
                 {
                     // When called from the Finalizer, we must not throw.
                     // But when reference counting goes wrong, ConsumedCapability.Release() will throw an InvalidOperationException.
                     // The only option here is to suppress that exception.
-                    try { ConsumedCap?.Release(); }
+                    try { _consumedCap?.Release(); }
                     catch { }
                 }
 
@@ -187,7 +192,7 @@ namespace Capnp.Rpc
         ~Proxy()
         {
 #if DebugFinalizers
-            Logger?.LogWarning($"Caught orphaned Proxy, created from here: {CreatorStackTrace}.");
+            Debugger.Log(0, "DebugFinalizers", $"Caught orphaned Proxy, created from here: {CreatorStackTrace}.");
 #endif
 
             Dispose(false);
diff --git a/Capnp.Net.Runtime/Rpc/RpcEngine.cs b/Capnp.Net.Runtime/Rpc/RpcEngine.cs
index 5a55cd6..c271d53 100644
--- a/Capnp.Net.Runtime/Rpc/RpcEngine.cs
+++ b/Capnp.Net.Runtime/Rpc/RpcEngine.cs
@@ -66,7 +66,7 @@ namespace Capnp.Rpc
                 Dismissed
             }
 
-            static readonly ThreadLocal<PendingQuestion?> _tailCall = new ThreadLocal<PendingQuestion?>();
+            static readonly ThreadLocal<PendingQuestion?> _deferredCall = new ThreadLocal<PendingQuestion?>();
             static readonly ThreadLocal<bool> _canDeferCalls = new ThreadLocal<bool>();
 
             ILogger Logger { get; } = Logging.CreateLogger<RpcEndpoint>();
@@ -81,6 +81,7 @@ namespace Capnp.Rpc
             readonly Dictionary<uint, PendingAnswer> _answerTable = new Dictionary<uint, PendingAnswer>();
             readonly Dictionary<uint, TaskCompletionSource<int>> _pendingDisembargos = new Dictionary<uint, TaskCompletionSource<int>>();
             readonly object _reentrancyBlocker = new object();
+            readonly object _callReturnBlocker = new object();
 
             long _recvCount;
             long _sendCount;
@@ -284,16 +285,8 @@ namespace Capnp.Rpc
 
                     if (_revExportTable.TryGetValue(providedCapability, out uint id))
                     {
+                        _exportTable[id].AddRef();
                         first = false;
-
-                        if (_exportTable.TryGetValue(id, out var rc))
-                        {
-                            rc.AddRef();
-                        }
-                        else
-                        {
-                            Logger.LogError("Inconsistent export table: Capability with id {0} exists in reverse table only", id);
-                        }
                     }
                     else
                     {
@@ -305,7 +298,6 @@ namespace Capnp.Rpc
 
                         _revExportTable.Add(providedCapability, id);
                         _exportTable.Add(id, new RefCounted<Skeleton>(providedCapability));
-
                         first = true;
                     }
 
@@ -407,8 +399,22 @@ namespace Capnp.Rpc
                 }
             }
 
+            void DispatchDeferredCalls()
+            {
+                var call = _deferredCall.Value;
+                _deferredCall.Value = null;
+                call?.Send();
+            }
 
             void ProcessCall(Call.READER req)
+            {
+                lock (_callReturnBlocker)
+                {
+                    ProcessCallLocked(req);
+                }
+            }
+
+            void ProcessCallLocked(Call.READER req)
             {
                 Return.WRITER SetupReturn(MessageBuilder mb)
                 {
@@ -420,8 +426,10 @@ namespace Capnp.Rpc
                     return ret;
                 }
 
-                void ReturnCall(Action<Return.WRITER> why)
+                void ReturnCallNoCapTable(Action<Return.WRITER> why)
                 {
+                    DispatchDeferredCalls();
+
                     var mb = MessageBuilder.Create();
                     mb.InitCapTable();
                     var ret = SetupReturn(mb);
@@ -430,7 +438,10 @@ namespace Capnp.Rpc
 
                     try
                     {
-                        Tx(mb.Frame);
+                        lock (_callReturnBlocker)
+                        {
+                            Tx(mb.Frame);
+                        }
                     }
                     catch (RpcException exception)
                     {
@@ -473,7 +484,7 @@ namespace Capnp.Rpc
                                     {
                                         Debug.Fail("Either answer or counter question must be present");
                                     }
-                                    else if (aorcq.Answer != null || aorcq.Counterquestion != _tailCall.Value)
+                                    else if (aorcq.Answer != null || aorcq.Counterquestion != _deferredCall.Value)
                                     {
                                         var results = aorcq.Answer ?? (DynamicSerializerState)(await aorcq.Counterquestion!.WhenReturned);
                                         var ret = SetupReturn(results.MsgBuilder!);
@@ -484,12 +495,13 @@ namespace Capnp.Rpc
                                                 ret.which = Return.WHICH.Results;
                                                 ret.Results!.Content = results.Rewrap<DynamicSerializerState>();
                                                 ret.ReleaseParamCaps = releaseParamCaps;
+                                                DispatchDeferredCalls();
                                                 ExportCapTableAndSend(results, ret.Results);
                                                 pendingAnswer.CapTable = ret.Results.CapTable;
                                                 break;
 
                                             case Call.sendResultsTo.WHICH.Yourself:
-                                                ReturnCall(ret2 =>
+                                                ReturnCallNoCapTable(ret2 =>
                                                 {
                                                     ret2.which = Return.WHICH.ResultsSentElsewhere;
                                                     ret2.ReleaseParamCaps = releaseParamCaps;
@@ -499,11 +511,11 @@ namespace Capnp.Rpc
                                     }
                                     else if (aorcq.Counterquestion != null)
                                     {
-                                        _tailCall.Value = null;
+                                        _deferredCall.Value = null;
                                         aorcq.Counterquestion.IsTailCall = true;
                                         aorcq.Counterquestion.Send();
 
-                                        ReturnCall(ret2 =>
+                                        ReturnCallNoCapTable(ret2 =>
                                         {
                                             ret2.which = Return.WHICH.TakeFromOtherQuestion;
                                             ret2.TakeFromOtherQuestion = aorcq.Counterquestion.QuestionId;
@@ -513,7 +525,7 @@ namespace Capnp.Rpc
                                 }
                                 catch (TaskCanceledException)
                                 {
-                                    ReturnCall(ret =>
+                                    ReturnCallNoCapTable(ret =>
                                     {
                                         ret.which = Return.WHICH.Canceled;
                                         ret.ReleaseParamCaps = releaseParamCaps;
@@ -521,7 +533,7 @@ namespace Capnp.Rpc
                                 }
                                 catch (System.Exception exception)
                                 {
-                                    ReturnCall(ret =>
+                                    ReturnCallNoCapTable(ret =>
                                     {
                                         ret.which = Return.WHICH.Exception;
                                         ret.Exception!.Reason = exception.Message;
@@ -543,7 +555,7 @@ namespace Capnp.Rpc
                                 }
                                 finally
                                 {
-                                    ReturnCall(ret =>
+                                    ReturnCallNoCapTable(ret =>
                                     {
                                         ret.which = Return.WHICH.ResultsSentElsewhere;
                                         ret.ReleaseParamCaps = releaseParamCaps;
@@ -600,7 +612,7 @@ namespace Capnp.Rpc
                 }
 
                 _canDeferCalls.Value = true;
-                Impatient.AskingEndpoint = this;
+                Impatient.PushAskingEndpoint(this);
 
                 try
                 {
@@ -683,10 +695,8 @@ namespace Capnp.Rpc
                 finally
                 {
                     _canDeferCalls.Value = false;
-                    Impatient.AskingEndpoint = null;
-                    var call = _tailCall.Value;
-                    _tailCall.Value = null;
-                    call?.Send();
+                    Impatient.PopAskingEndpoint();
+                    DispatchDeferredCalls();
                 }
             }
 
@@ -1419,8 +1429,8 @@ namespace Capnp.Rpc
 
                 if (_canDeferCalls.Value)
                 {
-                    _tailCall.Value?.Send();
-                    _tailCall.Value = question;
+                    DispatchDeferredCalls();
+                    _deferredCall.Value = question;
                 }
                 else
                 {
diff --git a/Capnp.Net.Runtime/Rpc/Vine.cs b/Capnp.Net.Runtime/Rpc/Vine.cs
index 3572f6c..1c4f29c 100644
--- a/Capnp.Net.Runtime/Rpc/Vine.cs
+++ b/Capnp.Net.Runtime/Rpc/Vine.cs
@@ -76,7 +76,12 @@ namespace Capnp.Rpc
 
         protected override void Dispose(bool disposing)
         {
-            Proxy.Dispose();
+            if (disposing)
+                Proxy.Dispose();
+            else
+                try { Proxy.Dispose(); }
+                catch { }
+
             base.Dispose(disposing);
         }
     }