diff --git a/Octokit.Tests/Http/ConnectionTests.cs b/Octokit.Tests/Http/ConnectionTests.cs
index 23582e5cc8..dcf12016d7 100644
--- a/Octokit.Tests/Http/ConnectionTests.cs
+++ b/Octokit.Tests/Http/ConnectionTests.cs
@@ -306,21 +306,30 @@ public class ThePatchMethod
             [Fact]
             public async Task RunsConfiguredAppWithAppropriateEnv()
             {
-                string data = SimpleJson.SerializeObject(new object());
-                var httpClient = Substitute.For<IHttpClient>();
+                var body = new object();
+                var expectedData = SimpleJson.SerializeObject(body);
+
+                var serializer = Substitute.For<IJsonSerializer>();
+                serializer.Serialize(body).Returns(expectedData);
+
                 IResponse response = new Response();
-                httpClient.Send(Args.Request, Args.CancellationToken).Returns(Task.FromResult(response));
+                var httpClient = Substitute.For<IHttpClient>();
+                httpClient.Send(Args.Request, Args.CancellationToken)
+                    .Returns(Task.FromResult(response));
+
                 var connection = new Connection(new ProductHeaderValue("OctokitTests"),
                     _exampleUri,
                     Substitute.For<ICredentialStore>(),
                     httpClient,
-                    Substitute.For<IJsonSerializer>());
+                    serializer);
 
-                await connection.Patch<string>(new Uri("endpoint", UriKind.Relative), new object());
+                await connection.Patch<string>(new Uri("endpoint", UriKind.Relative), body);
+
+                serializer.Received(1).Serialize(body);
 
                 httpClient.Received(1).Send(Arg.Is<IRequest>(req =>
                     req.BaseAddress == _exampleUri &&
-                    (string)req.Body == data &&
+                    (string)req.Body == expectedData &&
                     req.Method == HttpVerb.Patch &&
                     req.ContentType == "application/x-www-form-urlencoded" &&
                     req.Endpoint == new Uri("endpoint", UriKind.Relative)), Args.CancellationToken);
@@ -350,18 +359,24 @@ public class ThePutMethod
             public async Task MakesPutRequestWithData()
             {
                 var body = new object();
+                var serializer = Substitute.For<IJsonSerializer>();
                 var expectedBody = SimpleJson.SerializeObject(body);
                 var httpClient = Substitute.For<IHttpClient>();
                 IResponse response = new Response();
+
+                serializer.Serialize(body).Returns(expectedBody);
+
                 httpClient.Send(Args.Request, Args.CancellationToken).Returns(Task.FromResult(response));
                 var connection = new Connection(new ProductHeaderValue("OctokitTests"),
                     _exampleUri,
                     Substitute.For<ICredentialStore>(),
                     httpClient,
-                    Substitute.For<IJsonSerializer>());
+                    serializer);
 
                 await connection.Put<string>(new Uri("endpoint", UriKind.Relative), body);
 
+                serializer.Received(1).Serialize(body);
+
                 httpClient.Received(1).Send(Arg.Is<IRequest>(req =>
                     req.BaseAddress == _exampleUri &&
                     (string)req.Body == expectedBody &&
@@ -374,18 +389,25 @@ public async Task MakesPutRequestWithData()
             public async Task MakesPutRequestWithNoData()
             {
                 var body = RequestBody.Empty;
+                var serializer = Substitute.For<IJsonSerializer>();
                 var expectedBody = SimpleJson.SerializeObject(body);
                 var httpClient = Substitute.For<IHttpClient>();
                 IResponse response = new Response();
+
+                serializer.Serialize(body).Returns(expectedBody);
+
                 httpClient.Send(Args.Request, Args.CancellationToken).Returns(Task.FromResult(response));
+
                 var connection = new Connection(new ProductHeaderValue("OctokitTests"),
                     _exampleUri,
                     Substitute.For<ICredentialStore>(),
                     httpClient,
-                    Substitute.For<IJsonSerializer>());
+                    serializer);
 
                 await connection.Put<string>(new Uri("endpoint", UriKind.Relative), body);
 
+                serializer.Received(1).Serialize(body);
+
                 httpClient.Received(1).Send(Arg.Is<IRequest>(req =>
                     req.BaseAddress == _exampleUri &&
                     (string)req.Body == expectedBody &&
@@ -397,18 +419,24 @@ public async Task MakesPutRequestWithNoData()
             public async Task MakesPutRequestWithDataAndTwoFactor()
             {
                 var body = new object();
+                var serializer = Substitute.For<IJsonSerializer>();
                 var expectedBody = SimpleJson.SerializeObject(body);
                 var httpClient = Substitute.For<IHttpClient>();
                 IResponse response = new Response();
+
+                serializer.Serialize(body).Returns(expectedBody);
+
                 httpClient.Send(Args.Request, Args.CancellationToken).Returns(Task.FromResult(response));
                 var connection = new Connection(new ProductHeaderValue("OctokitTests"),
                     _exampleUri,
                     Substitute.For<ICredentialStore>(),
                     httpClient,
-                    Substitute.For<IJsonSerializer>());
+                    serializer);
 
                 await connection.Put<string>(new Uri("endpoint", UriKind.Relative), body, "two-factor");
 
+                serializer.Received(1).Serialize(body);
+
                 httpClient.Received(1).Send(Arg.Is<IRequest>(req =>
                     req.BaseAddress == _exampleUri &&
                     (string)req.Body == expectedBody &&
@@ -422,18 +450,24 @@ public async Task MakesPutRequestWithDataAndTwoFactor()
             public async Task MakesPutRequestWithNoDataAndTwoFactor()
             {
                 var body = RequestBody.Empty;
+                var serializer = Substitute.For<IJsonSerializer>();
                 var expectedBody = SimpleJson.SerializeObject(body);
                 var httpClient = Substitute.For<IHttpClient>();
                 IResponse response = new Response();
+
+                serializer.Serialize(body).Returns(expectedBody);
+
                 httpClient.Send(Args.Request, Args.CancellationToken).Returns(Task.FromResult(response));
                 var connection = new Connection(new ProductHeaderValue("OctokitTests"),
                     _exampleUri,
                     Substitute.For<ICredentialStore>(),
                     httpClient,
-                    Substitute.For<IJsonSerializer>());
+                    serializer);
 
                 await connection.Put<string>(new Uri("endpoint", UriKind.Relative), body, "two-factor");
 
+                serializer.Received(1).Serialize(body);
+
                 httpClient.Received(1).Send(Arg.Is<IRequest>(req =>
                     req.BaseAddress == _exampleUri &&
                     (string)req.Body == expectedBody &&
@@ -448,17 +482,24 @@ public class ThePostMethod
             [Fact]
             public async Task SendsProperlyFormattedPostRequest()
             {
-                string data = SimpleJson.SerializeObject(new object());
+                var body = new object();
+                var serializer = Substitute.For<IJsonSerializer>();
+                var data = SimpleJson.SerializeObject(body);
                 var httpClient = Substitute.For<IHttpClient>();
                 IResponse response = new Response();
+
+                serializer.Serialize(body).Returns(data);
+
                 httpClient.Send(Args.Request, Args.CancellationToken).Returns(Task.FromResult(response));
                 var connection = new Connection(new ProductHeaderValue("OctokitTests"),
                     _exampleUri,
                     Substitute.For<ICredentialStore>(),
                     httpClient,
-                    Substitute.For<IJsonSerializer>());
+                    serializer);
+
+                await connection.Post<string>(new Uri("endpoint", UriKind.Relative), body, null, null);
 
-                await connection.Post<string>(new Uri("endpoint", UriKind.Relative), new object(), null, null);
+                serializer.Received(1).Serialize(body);
 
                 httpClient.Received(1).Send(Arg.Is<IRequest>(req =>
                     req.BaseAddress == _exampleUri &&
diff --git a/Octokit/Http/Connection.cs b/Octokit/Http/Connection.cs
index dabee2710b..ba1035d728 100644
--- a/Octokit/Http/Connection.cs
+++ b/Octokit/Http/Connection.cs
@@ -133,7 +133,7 @@ public Connection(
             BaseAddress = baseAddress;
             _authenticator = new Authenticator(credentialStore);
             _httpClient = httpClient;
-            _jsonPipeline = new JsonHttpPipeline();
+            _jsonPipeline = new JsonHttpPipeline(serializer);
         }
 
         /// <summary>