Loading model function

[eluser]DaTran[/eluser]
I created My_Model.php in the library's folder but it's giving an error on line 3

Code:

Fatal error: Class 'CI_Model' not found in ......./application/libraries/MY_Model.php on line 3

Code:

<?php

class My_Model extends CI_Model
{
    function eatmyfood()
    {
        echo 'EAT MY FOOD';
    }
}