   """
   @spec extname(t) :: binary
   def extname(path) do
-    FN.extension(IO.chardata_to_string(path))
+    :filename.extension(IO.chardata_to_string(path))
   end
 
   @doc """

  """
  @spec basename(t) :: binary
  def basename(path) do
    FN.basename(IO.chardata_to_string(path))
  end

  @doc """

  """
  @spec dirname(t) :: binary
  def dirname(path) do
    :filename.dirname(IO.chardata_to_string(path))
  end

  @doc """
