diff --git a/core/model/Hierarchy.php b/core/model/Hierarchy.php
index 8017f3b2e..2ad230a7e 100755
--- a/core/model/Hierarchy.php
+++ b/core/model/Hierarchy.php
@@ -369,7 +369,10 @@ class Hierarchy extends DataObjectDecorator {
 					continue;
 				}
 				$idList[] = $child->ID;
-				$child->getExtensionInstance('Hierarchy')->loadDescendantIDListInto($idList);
+				$ext = $child->getExtensionInstance('Hierarchy');
+				$ext->setOwner($child);
+				$ext->loadDescendantIDListInto($idList);
+				$ext->clearOwner();
 			}
 		}
 	}
diff --git a/tests/model/HierarchyTest.php b/tests/model/HierarchyTest.php
index 304e3bae5..977afaebe 100644
--- a/tests/model/HierarchyTest.php
+++ b/tests/model/HierarchyTest.php
@@ -101,7 +101,9 @@ class HierarchyTest extends SapphireTest {
 		
 		$this->assertContains($page2a->ID, $page2IdList);
 		$this->assertContains($page2b->ID, $page2IdList);
-		$this->assertEquals(2, count($page2IdList));
+		$this->assertContains($page2aa->ID, $page2IdList);
+		$this->assertContains($page2ab->ID, $page2IdList);
+		$this->assertEquals(4, count($page2IdList));
 		
 		$this->assertContains($page2aa->ID, $page2aIdList);
 		$this->assertContains($page2ab->ID, $page2aIdList);