diff --git a/Octokit.Tests/Http/HttpClientAdapterTests.cs b/Octokit.Tests/Http/HttpClientAdapterTests.cs
index 6099df52..612f3811 100644
--- a/Octokit.Tests/Http/HttpClientAdapterTests.cs
+++ b/Octokit.Tests/Http/HttpClientAdapterTests.cs
@@ -74,6 +74,7 @@ namespace Octokit.Tests.Http
 
                 Assert.NotNull(requestMessage.Content);
                 Assert.IsType<StreamContent>(requestMessage.Content);
+                Assert.Equal("text/plain", requestMessage.Content.Headers.ContentType.MediaType);
             }
 
             [Fact]
diff --git a/Octokit/Http/HttpClientAdapter.cs b/Octokit/Http/HttpClientAdapter.cs
index 7dd3c690..8fc40088 100644
--- a/Octokit/Http/HttpClientAdapter.cs
+++ b/Octokit/Http/HttpClientAdapter.cs
@@ -96,6 +96,7 @@ namespace Octokit.Internal
                 if (bodyStream != null)
                 {
                     requestMessage.Content = new StreamContent(bodyStream);
+                    requestMessage.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(request.ContentType);
                 }
             }
             catch (Exception)