diff --git a/.appveyor.yml b/.appveyor.yml
index eb25a73..648f701 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -1,4 +1,5 @@
 version: '{build}'
+skip_branch_with_pr: true
 image: Visual Studio 2017
 install:
   - cmd: cd src
@@ -6,4 +7,7 @@ build_script:
   - cmd: dotnet build Castle.Sdk -c Release -f netstandard2.0
   - cmd: dotnet build Castle.Sdk -c Release -f net461
 test_script:
-  - cmd: dotnet test Tests
\ No newline at end of file
+  - ps: nuget install OpenCover -OutputDirectory packages -Version 4.7.922
+  - ps: dotnet tool install coveralls.net --tool-path tools
+  - ps: .\packages\OpenCover.4.7.922\tools\OpenCover.Console.exe -register:user -target:dotnet.exe -targetargs:"test Tests\Tests.csproj" -filter:"+[Castle.Sdk*]*" -oldStyle -output:opencoverCoverage.xml
+  - ps: .\tools\csmacnz.coveralls.exe --opencover -i opencoverCoverage.xml --repoToken $env:COVERALLS_REPO_TOKEN --commitId $env:APPVEYOR_REPO_COMMIT --commitBranch $env:APPVEYOR_REPO_BRANCH --commitAuthor $env:APPVEYOR_REPO_COMMIT_AUTHOR --commitEmail $env:APPVEYOR_REPO_COMMIT_AUTHOR_EMAIL --commitMessage $env:APPVEYOR_REPO_COMMIT_MESSAGE --jobId $env:APPVEYOR_JOB_ID
diff --git a/src/Castle.Sdk/Infrastructure/HttpMessageSender.cs b/src/Castle.Sdk/Infrastructure/HttpMessageSender.cs
index 5676955..acbfc8a 100644
--- a/src/Castle.Sdk/Infrastructure/HttpMessageSender.cs
+++ b/src/Castle.Sdk/Infrastructure/HttpMessageSender.cs
@@ -32,7 +32,7 @@ public HttpMessageSender(CastleConfiguration configuration, IInternalLogger logg
         public async Task<TResponse> Post<TResponse>(string endpoint, object payload)
             where TResponse : class, new()
         {
-            var jsonContent = PayloadToJson(payload);
+            var jsonContent = payload.ToHttpContent();
             var message = new HttpRequestMessage(HttpMethod.Post, endpoint)
             {
                 Content = jsonContent
@@ -58,7 +58,7 @@ public async Task<TResponse> Put<TResponse>(string endpoint)
         public async Task<TResponse> Delete<TResponse>(string endpoint, object payload)
             where TResponse : class, new()
         {
-            var jsonContent = PayloadToJson(payload);
+            var jsonContent = payload.ToHttpContent();
             var message = new HttpRequestMessage(HttpMethod.Delete, endpoint)
             {
                 Content = jsonContent
@@ -91,14 +91,6 @@ private async Task<TResponse> SendRequest<TResponse>(HttpRequestMessage requestM
                     requestMessage.RequestUri.AbsoluteUri, 
                     (int)_httpClient.Timeout.TotalMilliseconds);
             }
-        }
-
-        private static StringContent PayloadToJson(object payload)
-        {
-            return new StringContent(
-                JsonForCastle.SerializeObject(payload), 
-                Encoding.UTF8, 
-                "application/json");
-        }
+        }      
     }
 }
diff --git a/src/Tests/When_creating_configuration.cs b/src/Tests/When_creating_configuration.cs
index 3175d47..b7c76b2 100644
--- a/src/Tests/When_creating_configuration.cs
+++ b/src/Tests/When_creating_configuration.cs
@@ -14,5 +14,13 @@ public void Should_always_add_Cookie_when_setting_blacklist(CastleConfiguration
 
             configuration.Blacklist.Should().Contain("Cookie");
         }
+
+        [Fact]
+        public void Should_be_able_to_get_recommended_whitelist()
+        {
+            var result = Castle.Headers.Whitelist;
+
+            result.Should().NotBeEmpty();
+        }
     }
 }