   ###
   findOne: (selector, options) ->
     console.info "[FilesCollection] [findOne(#{JSON.stringify(selector)}, #{JSON.stringify(options)})]" if @debug
-    check selector, Match.Optional Match.OneOf Object, String, Boolean, null
+    check selector, Match.Optional Match.OneOf Object, String, Boolean, Number, null
     check options, Match.Optional Object
 
     selector = {} unless arguments.length

        return true to continue
        return false to abort upload
  @param {Boolean} autoStart     - Start upload immediately. If set to false, you need manually call .start() method on returned class. Useful to set EventListeners.
  @summary Upload file to server over DDP
  @returns {UploadInstance} Instance. UploadInstance has next properties:
    {ReactiveVar} onPause  - Is upload process on the pause?
    {ReactiveVar} state    - active|paused|aborted|completed

        onUploaded:      Match.Optional Function
        onProgress:      Match.Optional Function
        onBeforeUpload:  Match.Optional Function
        allowWebWorkers: Boolean
        ddp:             Match.Any
      }

      if not @config.fileName and not @config.file.name
