- <dc:date><?php echo mysql2date('Y-m-d\TH:i:s\Z', get_lastpostmodified('GMT'), false); ?></dc:date>
+ <dc:date><?php
+ $date = get_lastpostmodified( 'GMT' );
+ echo $date ? mysql2date( 'Y-m-d\TH:i:s\Z', $date ) : date( 'Y-m-d\TH:i:s\Z' );
+ ?></dc:date>