Parse error in custom function for Gravity Forms

Hello,

PHP newbie here. Have tried to write a custom function for use with Gravity Forms. Have created a child them and that’s all good.

Purpose of function: to take a value from a date picker field and return what day of the week it is.

Have added this into functions.php and added to child theme:

<?php
/**
 * Use Gravity Forms Conditional Logic with Dates
 */Returns day of week of selected date

add_filter("gform_field_value_dayofweek", "liz_populate_dayofweek");
function liz_populate_dayofweek( $value ){
    $timestamp = (strtotime($value))
    $day = date('l', $timestamp);
    return $day;
}
?>

Which gives the following error:
: syntax error, unexpected T_STRING in …line 4 of child theme functions.php

Can anyone help me out here please?
Many thanks!!