diff --git a/src/Hosting/TestHost/src/HttpContextBuilder.cs b/src/Hosting/TestHost/src/HttpContextBuilder.cs
index 287e4aacf7b2..de3ec58709b8 100644
--- a/src/Hosting/TestHost/src/HttpContextBuilder.cs
+++ b/src/Hosting/TestHost/src/HttpContextBuilder.cs
@@ -127,6 +127,9 @@ internal void AbortRequest()
 
         internal async Task CompleteResponseAsync()
         {
+            // Flush any pending content in writer
+            await _httpContext.Response.BodyWriter.FlushAsync();
+
             _pipelineFinished = true;
             await ReturnResponseMessageAsync();
             _responseStream.CompleteWrites();
diff --git a/src/Hosting/TestHost/test/ClientHandlerTests.cs b/src/Hosting/TestHost/test/ClientHandlerTests.cs
index 75399284602c..5a6b6b6de2ef 100644
--- a/src/Hosting/TestHost/test/ClientHandlerTests.cs
+++ b/src/Hosting/TestHost/test/ClientHandlerTests.cs
@@ -5,6 +5,7 @@
 using System.IO;
 using System.Linq;
 using System.Net.Http;
+using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
@@ -267,6 +268,24 @@ public async Task HeadersAvailableBeforeBodyFinished()
             Assert.Equal("BodyStarted,BodyFinished", await response.Content.ReadAsStringAsync());
         }
 
+        [Fact]
+        public async Task PendingContentInWriterIsSent()
+        {
+            var handler = new ClientHandler(PathString.Empty, new DummyApplication(context =>
+            {
+                var data = Encoding.UTF8.GetBytes("Hello world");
+
+                var span = context.Response.BodyWriter.GetSpan(data.Length);
+                data.CopyTo(span);
+                context.Response.BodyWriter.Advance(data.Length);
+
+                return Task.CompletedTask;
+            }));
+            var httpClient = new HttpClient(handler);
+            HttpResponseMessage response = await httpClient.GetAsync("https://example.com/");
+            Assert.Equal("Hello world", await response.Content.ReadAsStringAsync());
+        }
+
         [Fact]
         public async Task FlushSendsHeaders()
         {
diff --git a/src/Hosting/WindowsServices/src/Microsoft.AspNetCore.Hosting.WindowsServices.csproj b/src/Hosting/WindowsServices/src/Microsoft.AspNetCore.Hosting.WindowsServices.csproj
index 00037213e0a7..3ea91fde9f82 100644
--- a/src/Hosting/WindowsServices/src/Microsoft.AspNetCore.Hosting.WindowsServices.csproj
+++ b/src/Hosting/WindowsServices/src/Microsoft.AspNetCore.Hosting.WindowsServices.csproj
@@ -16,9 +16,7 @@
     <Reference Include="System.ServiceProcess.ServiceController" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Update="WebHostService.cs">
-      <SubType>Component</SubType>
-    </Compile>
+    <Compile Update="WebHostService.cs" />
   </ItemGroup>
 
 </Project>