diff --git a/Classes/Common/MetsDocument.php b/Classes/Common/MetsDocument.php
index 69a368784..f1ae0971a 100644
--- a/Classes/Common/MetsDocument.php
+++ b/Classes/Common/MetsDocument.php
@@ -547,7 +547,7 @@ private function getSubentries($allSubentries, string $parentIndex, \DOMNode $pa
             if ($subentry['parent_index_name'] == $parentIndex) {
                 $values = $domXPath->evaluate($subentry['xpath'], $parentNode);
                 if (!empty($subentry['xpath']) && ($values)) {
-                    array_merge($theseSubentries, $this->getSubentryValue($values, $subentry));
+                    $theseSubentries = array_merge($theseSubentries, $this->getSubentryValue($values, $subentry));
                 }
                 // Set default value if applicable.
                 if (