diff --git a/plugins/importexport/users/filter/PKPUserUserXmlFilter.php b/plugins/importexport/users/filter/PKPUserUserXmlFilter.php
index 6ed3c357152..abf91486b6e 100644
--- a/plugins/importexport/users/filter/PKPUserUserXmlFilter.php
+++ b/plugins/importexport/users/filter/PKPUserUserXmlFilter.php
@@ -160,7 +160,8 @@ public function addUserGroups($doc, $rootNode)
         $exportFilter = array_shift($userGroupExportFilters);
         $exportFilter->setDeployment($this->getDeployment());
 
-        $userGroupsDoc = $exportFilter->execute($userGroups->all());
+        $userGroupsArray = $userGroups->all();
+        $userGroupsDoc = $exportFilter->execute($userGroupsArray);
         if ($userGroupsDoc->documentElement instanceof \DOMElement) {
             $clone = $doc->importNode($userGroupsDoc->documentElement, true);
             $rootNode->appendChild($clone);