diff --git a/lib/docker/image.rb b/lib/docker/image.rb
index 4e17531f6..b7614eeeb 100644
--- a/lib/docker/image.rb
+++ b/lib/docker/image.rb
@@ -252,6 +252,7 @@ def build(commands, opts = {}, connection = Docker.connection, &block)
       body = ""
       connection.post(
         '/build', opts,
+        :headers => { 'Content-Type' => 'application/tar' },
         :body => Docker::Util.create_tar('Dockerfile' => commands),
         :response_block => response_block(body, &block)
       )