diff --git a/CHANGELOG.md b/CHANGELOG.md
index c0ff3d765b..e40d4a40f2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ The format is mostly based on [Keep a Changelog](https://keepachangelog.com/en/1
 - Add DB index for news_feeds.deleted_at (#2526)
 
 ### Fixed
+- Mark over 65535 unread items as "read"
 
 # Releases
 ## [25.0.0-alpha3] - 2023-12-24
diff --git a/lib/Db/FeedMapperV2.php b/lib/Db/FeedMapperV2.php
index c80bf118b3..7015dc53b0 100644
--- a/lib/Db/FeedMapperV2.php
+++ b/lib/Db/FeedMapperV2.php
@@ -186,21 +186,27 @@ function ($value): int {
             },
             $this->db->executeQuery($idBuilder->getSQL(), $idBuilder->getParameters())->fetchAll()
         );
-        $time = new Time();
-        $builder = $this->db->getQueryBuilder();
-        $builder->update(ItemMapperV2::TABLE_NAME)
-            ->set('unread', $builder->createParameter('unread'))
-            ->set('last_modified', $builder->createParameter('last_modified'))
-            ->andWhere('id IN (:idList)')
-            ->andWhere('unread != :unread')
-            ->setParameter('unread', false, IQueryBuilder::PARAM_BOOL)
-            ->setParameter('idList', $idList, IQueryBuilder::PARAM_INT_ARRAY)
-            ->setParameter('last_modified', $time->getMicroTime(), IQueryBuilder::PARAM_STR);
-
-        return $this->db->executeStatement(
-            $builder->getSQL(),
-            $builder->getParameters(),
-            $builder->getParameterTypes()
-        );
+
+        $chunked_idList = array_chunk($idList, 65500);
+        $res = 0;
+        foreach ($chunked_idList as $idList_chunk) {
+            $time = new Time();
+            $builder = $this->db->getQueryBuilder();
+            $builder->update(ItemMapperV2::TABLE_NAME)
+                ->set('unread', $builder->createParameter('unread'))
+                ->set('last_modified', $builder->createParameter('last_modified'))
+                ->andWhere('id IN (:idList)')
+                ->andWhere('unread != :unread')
+                ->setParameter('unread', false, IQueryBuilder::PARAM_BOOL)
+                ->setParameter('idList', $idList_chunk, IQueryBuilder::PARAM_INT_ARRAY)
+                ->setParameter('last_modified', $time->getMicroTime(), IQueryBuilder::PARAM_STR);
+
+            $res += $this->db->executeStatement(
+                $builder->getSQL(),
+                $builder->getParameters(),
+                $builder->getParameterTypes()
+            );
+        }
+        return $res;
     }
 }