       type: 'POST'
       url: url
       data: pako.deflate(JSON.stringify sendContent)
+      contentType: mimeType
       processData: false
       beforeSend: (xhr) ->
         xhr.setRequestHeader('Content-Encoding', 'deflate')

    if diff? and diffJson.length < contentJson.length
      sendContent = diffJson
      url = patchDocumentUrl
    else
      if metadata.name then params.recordname = metadata.name
      url = saveDocumentUrl

    if metadata.providerData.id then params.recordid = metadata.providerData.id

    # See if we can patch
    mimeType = @options.mimeType or 'application/json'
    contentJson = JSON.stringify content
    canOverwrite = metadata.overwritable and @previouslySavedContent?
    if canOverwrite and diff = @_createDiff @previouslySavedContent.getContent(), content
