diff --git a/src/System.Private.ServiceModel/src/System/ServiceModel/ClientBase.cs b/src/System.Private.ServiceModel/src/System/ServiceModel/ClientBase.cs
index a83417d7bf8..56c573b0254 100644
--- a/src/System.Private.ServiceModel/src/System/ServiceModel/ClientBase.cs
+++ b/src/System.Private.ServiceModel/src/System/ServiceModel/ClientBase.cs
@@ -308,6 +308,7 @@ public Task OpenAsync()
         private async Task OpenAsync(TimeSpan timeout)
         {
             TimeoutHelper timeoutHelper = new TimeoutHelper(timeout);
+            await TaskHelpers.EnsureDefaultTaskScheduler();
             if (!_useCachedFactory)
             {
                 await GetChannelFactory().OpenHelperAsync(timeoutHelper.RemainingTime());
@@ -368,6 +369,7 @@ private async Task CloseAsync(TimeSpan timeout)
                 }
 
                 TimeoutHelper timeoutHelper = new TimeoutHelper(timeout);
+                await TaskHelpers.EnsureDefaultTaskScheduler();
                 if (_channel != null)
                 {
                     await InnerChannel.CloseHelperAsync(timeoutHelper.RemainingTime());
diff --git a/src/System.Private.ServiceModel/tests/Common/Infrastructure/xunit/WcfTestCase.cs b/src/System.Private.ServiceModel/tests/Common/Infrastructure/xunit/WcfTestCase.cs
index 497e98ed711..c3a1c1afa30 100644
--- a/src/System.Private.ServiceModel/tests/Common/Infrastructure/xunit/WcfTestCase.cs
+++ b/src/System.Private.ServiceModel/tests/Common/Infrastructure/xunit/WcfTestCase.cs
@@ -51,7 +51,7 @@ public override async Task<RunSummary> RunAsync(
             ConcurrentQueue<EventWrittenEventArgs> events = new ConcurrentQueue<EventWrittenEventArgs>();
 	        s_testListener.EventWritten = events.Enqueue;
             Timer timer = null;
-            if (_failFastDuration != System.Threading.Timeout.InfiniteTimeSpan)
+            if (_failFastDuration != System.Threading.Timeout.InfiniteTimeSpan && !System.Diagnostics.Debugger.IsAttached)
             {
                 timer = new Timer((s) => Environment.FailFast("Test timed out"),
                                   null,