diff --git a/source/WcfClientProxyGenerator.Tests/ProxyTests.cs b/source/WcfClientProxyGenerator.Tests/ProxyTests.cs
index 29a5f88..8fa8d7c 100644
--- a/source/WcfClientProxyGenerator.Tests/ProxyTests.cs
+++ b/source/WcfClientProxyGenerator.Tests/ProxyTests.cs
@@ -108,7 +108,39 @@ public void CreatingProxy_TrailingSlashOnNamespace()
 
             Assert.That(result, Is.EqualTo("hello"));
         }
-   
+
+        [Test, Description("Github issue #22")]
+        public async Task AsyncMethod_FromSyncMethodWithFaultContract_CanBeCalled()
+        {
+            var service = Substitute.For<ICustomAttributeService>();
+
+            service
+                .FaultMethod(Arg.Any<string>())
+                .Returns("hello");
+
+            var proxy = service.StartHostAndAsyncProxy();
+
+            var result = await proxy.CallAsync(m => m.FaultMethod(""));
+
+            Assert.That(result, Is.EqualTo("hello"));
+        }
+
+        [Test, Description("Github issue #22")]
+        public async Task AsyncMethod_FromSyncMethodWithKnownTypeAttribute_CanBeCalled()
+        {
+            var service = Substitute.For<ICustomAttributeService>();
+
+            service
+                .KnownTypeMethod(Arg.Any<string>())
+                .Returns("hello");
+
+            var proxy = service.StartHostAndAsyncProxy();
+
+            var result = await proxy.CallAsync(m => m.KnownTypeMethod(""));
+
+            Assert.That(result, Is.EqualTo("hello"));
+        }
+
         [Test]
         public void Proxy_ReturnsExpectedValue_WhenCallingService()
         {
diff --git a/source/WcfClientProxyGenerator/DynamicProxyTypeGenerator.cs b/source/WcfClientProxyGenerator/DynamicProxyTypeGenerator.cs
index e3adbf3..d387ec4 100644
--- a/source/WcfClientProxyGenerator/DynamicProxyTypeGenerator.cs
+++ b/source/WcfClientProxyGenerator/DynamicProxyTypeGenerator.cs
@@ -364,9 +364,16 @@ private static void GenerateAsyncTaskMethod(
 
             methodBuilder.SetCustomAttribute(cloneOperationContractAttribute());
 
+            var restrictedAttributeTypes = new[]
+            {
+                typeof(OperationContractAttribute),
+                typeof(FaultContractAttribute),
+                typeof(ServiceKnownTypeAttribute)
+            };
+
             var remainingCustomAttributes = methodInfo
                 .GetCustomAttributesData()
-                .Where(m => m.AttributeType != typeof(OperationContractAttribute));
+                .Where(m => !restrictedAttributeTypes.Contains(m.AttributeType));
 
             foreach (var builder in CloneCustomAttributes(remainingCustomAttributes))
                 methodBuilder.SetCustomAttribute(builder);