Cronjob outputs welcome message [SOLVED]

I've found a workaround, which involves modifying the is_cli() function inside the system/core/Common.php file:

PHP Code:

function is_cli()
{
   //the old part was:    
   //return (PHP_SAPI === 'cli' OR defined('STDIN'));  

   //this will do the trick":
    if( PHP_SAPI == 'cli' OR defined('STDIN') )
    {
        return TRUE;
    }
    
    if( empty($_SERVER['REMOTE_ADDR']) and !isset($_SERVER['HTTP_USER_AGENT']) and count($_SERVER['argv']) > 0) 
    {
        return TRUE;
    } 
    
    return FALSE;
} 


I know I shouldn't modify any system files, but what other options do I have?