Minor Bug on supporter-ads.php

When Supporter ads is activated, enabling the php error reporting gives the following message:
Notice: Undefined index: page in /var/www/sandbox/wp-content/mu-plugins/supporter-ads.php on line 49

Should line 49:
if ($_GET['page'] == 'supporter' && $supporter_ads_enable_additional_ad_free_blogs == '1') {

be changed to:
if (isset($_GET['page']) && $_GET['page'] == 'supporter' && $supporter_ads_enable_additional_ad_free_blogs == '1') {

Please advise.

Thanks.