diff --git a/typo3/sysext/seo/Classes/XmlSitemap/AbstractXmlSitemapDataProvider.php b/typo3/sysext/seo/Classes/XmlSitemap/AbstractXmlSitemapDataProvider.php
index 70cd3aaf3047..985ca20061ca 100644
--- a/typo3/sysext/seo/Classes/XmlSitemap/AbstractXmlSitemapDataProvider.php
+++ b/typo3/sysext/seo/Classes/XmlSitemap/AbstractXmlSitemapDataProvider.php
@@ -104,7 +104,7 @@ public function getLastModified(): int
         $lastMod = 0;
         foreach ($this->items as $item) {
             if ((int)$item['lastMod'] > $lastMod) {
-                $lastMod = $item['lastMod'];
+                $lastMod = (int)$item['lastMod'];
             }
         }
 
diff --git a/typo3/sysext/seo/Classes/XmlSitemap/RecordsXmlSitemapDataProvider.php b/typo3/sysext/seo/Classes/XmlSitemap/RecordsXmlSitemapDataProvider.php
index b0e4fab06ac2..0b79dcd87137 100644
--- a/typo3/sysext/seo/Classes/XmlSitemap/RecordsXmlSitemapDataProvider.php
+++ b/typo3/sysext/seo/Classes/XmlSitemap/RecordsXmlSitemapDataProvider.php
@@ -99,7 +99,7 @@ public function generateItems(): void
         foreach ($rows as $row) {
             $this->items[] = [
                 'data' => $row,
-                'lastMod' => $row[$lastModifiedField]
+                'lastMod' => (int)$row[$lastModifiedField]
             ];
         }
     }