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)