diff --git a/tools/maintenance.php b/tools/maintenance.php
index 33c0a4d4..abf53361 100644
--- a/tools/maintenance.php
+++ b/tools/maintenance.php
@@ -5,6 +5,56 @@
 
 require dirname(__FILE__) . '/inc/cli.php';
 
+function get_reports_by_board(): array {
+    $query = prepare("SELECT `board`, `post`, `id` FROM ``reports``");
+    $query->execute() or error(db_error($query));
+    return $query->fetchAll(PDO::FETCH_GROUP | PDO::FETCH_NUM);
+}
+
+function post_ids_by_board(array $reports): array {
+    $ret = [];
+    foreach ($reports as $board => $values) {
+        foreach ($values as $value) {
+            $ret[$board] ??= [];
+            $ret[$board][] = $value[0];
+        }
+    }
+    return $ret;
+}
+
+function filter_invalid_reports(array $board_post_ids, array $reports): array {
+    $invalid_reports = [];
+
+    foreach ($board_post_ids as $board => $post_ids) {
+        $query = query(sprintf('SELECT `id` FROM ``posts_%s`` WHERE `id` = ' . implode(' OR `id` = ', $post_ids), $board));
+        $existing_posts = $query->fetchAll(PDO::FETCH_COLUMN);
+
+        foreach ($reports[$board] as $values) {
+            list($post_id, $report_id) = $values;
+            if (!in_array($post_id, $existing_posts)) {
+                $invalid_reports[] = $report_id;
+            }
+        }
+    }
+
+    return $invalid_reports;
+}
+
+function get_report_ids(array $reports): array {
+    $ret = [];
+    foreach ($reports as $_board => $values) {
+        foreach ($values as $value) {
+            $report_id = $value[0];
+            $ret[] = $report_id;
+        }
+    }
+    return $ret;
+}
+
+function delete_reports(array $report_ids): int {
+    return query('DELETE FROM ``reports`` WHERE `id` = ' . implode(' OR `id` = ', $report_ids))->rowCount();
+}
+
 echo "Clearing expired bans...\n";
 $start = microtime(true);
 $deleted_count = Bans::purge($config['require_ban_view'], $config['purge_bans']);
@@ -19,7 +69,23 @@ $deleted_count = purge_old_antispam();
 $delta = microtime(true) - $start;
 echo "Deleted $deleted_count expired antispam in $delta seconds!\n";
 $time_tot = $delta;
-$deleted_tot = $deleted_count;
+$deleted_tot += $deleted_count;
+
+echo "Clearing invalid reports...\n";
+$start = microtime(true);
+$reports = get_reports_by_board();
+$report_ids = get_report_ids($reports);
+$board_post_ids = post_ids_by_board($reports);
+$invalid_reports = filter_invalid_reports($board_post_ids, $reports);
+if (!empty($invalid_reports)) {
+    $deleted_count = delete_reports($invalid_reports);
+} else {
+    $deleted_count = 0;
+}
+$delta = microtime(true) - $start;
+echo "Deleted $deleted_count invalid reports in $delta seconds!\n";
+$time_tot += $delta;
+$deleted_tot += $deleted_count;
 
 $time_tot = number_format((float)$time_tot, 4, '.', '');
 modLog("Deleted $deleted_tot expired entries in {$time_tot}s with maintenance tool");