diff --git a/core/model/SiteTree.php b/core/model/SiteTree.php
index 3088b72c9..71f434c18 100755
--- a/core/model/SiteTree.php
+++ b/core/model/SiteTree.php
@@ -1023,6 +1023,7 @@ class SiteTree extends DataObject implements PermissionProvider,i18nEntityProvid
 					// parents and then see which ones the user has permission on
 					$canEditSiteConfig = SiteConfig::current_site_config()->canEdit($memberID);
 					foreach($potentiallyInherited as $item) {
+						if (!isset($groupedByParent[$item->ParentID])) $groupedByParent[$item->ParentID] = array(); 
 						if ($item->ParentID) $groupedByParent[$item->ParentID][] = $item->ID;
 						else $result[$item->ID] = $canEditSiteConfig;
 					}