diff --git a/inc/anti-bot.php b/inc/anti-bot.php
index 15a2954e..90259e8d 100644
--- a/inc/anti-bot.php
+++ b/inc/anti-bot.php
@@ -191,7 +191,7 @@ class AntiBot {
 }
 
 function _create_antibot($board, $thread) {
-	global $purged_old_antispam;
+	global $config, $purged_old_antispam;
 
 	$antibot = new AntiBot(array($board, $thread));
 
@@ -200,6 +200,17 @@ function _create_antibot($board, $thread) {
 		query('DELETE FROM ``antispam`` WHERE `expires` < UNIX_TIMESTAMP()') or error(db_error());
 	}
 
+	if ($thread)
+		$query = prepare('UPDATE ``antispam`` SET `expires` = UNIX_TIMESTAMP() + :expires WHERE `board` = :board AND `thread` = :thread AND `expires` IS NULL');
+	else
+		$query = prepare('UPDATE ``antispam`` SET `expires` = UNIX_TIMESTAMP() + :expires WHERE `board` = :board AND `thread` IS NULL AND `expires` IS NULL');
+
+	$query->bindValue(':board', $board);
+	if ($thread)
+		$query->bindValue(':thread', $thread);
+	$query->bindValue(':expires', $config['spam']['hidden_inputs_expire']);
+	$query->execute() or error(db_error($query));
+
 	$query = prepare('INSERT INTO ``antispam`` VALUES (:board, :thread, :hash, UNIX_TIMESTAMP(), NULL, 0)');
 	$query->bindValue(':board', $board);
 	$query->bindValue(':thread', $thread);