Unix-time problem

Hi! I wrote this simple function to return the current date minus supplied number of years: function get_birthdate($age_in_years) { // get the current timestamp into an array $timestamp = time(); $date_time_array = getdate($timestamp); $hours = $date_time_array["hours"]; $minutes = $date_time_array["minutes"]; $seconds = $date_time_array["seconds"]; $month = $date_time_array["mon"]; $day = $date_time_array["mday"]; $year = $date_time_array["year"]; // use mktime to recreate the unix timestamp // subtracting age_low and age_high from the years $timestamp = mktime($hours, $minutes,$seconds ,$month, $day,$year - $age_in_years); $birthdate = strftime("%d/%m/%Y", $timestamp); return($birthdate); } You, obviously, call it like this: echo get_birthdate(1); Which would return a datestring that looks like this: 05/03/2000 Works nice, but the problem occurs when I try to subtract more than 31 years which is naturall since, as far as UNIX is concerned, the world didn't exist then. (Took me a while to figure this one out though.) Any clues on how to fix this so that I can go beyond the past 31 years? Sincerely, Nicklas