diff --git a/core/model/Hierarchy.php b/core/model/Hierarchy.php
index 35b59cb05..44a5a999b 100644
--- a/core/model/Hierarchy.php
+++ b/core/model/Hierarchy.php
@@ -354,7 +354,7 @@ class Hierarchy extends DataObjectDecorator {
 					continue;
 				}
 				$idList[] = $child->ID;
-				$child->loadDescendantIDListInto($idList);
+				$child->getExtensionInstance('Hierarchy')->loadDescendantIDListInto($idList);
 			}
 		}
 	}
@@ -403,7 +403,7 @@ class Hierarchy extends DataObjectDecorator {
 		// Cache the allChildren data, so that future requests will return the references to the same
 		// object.  This allows the mark..() system to work appropriately.
 		if(!$this->allChildren) {
-			$this->allChildren = $this->owner->stageChildren(true);
+			$this->allChildren = $this->owner ? $this->owner->stageChildren(true) : null;
 		}
 		
 		return $this->allChildren;
diff --git a/tests/model/HierarchyTest.php b/tests/model/HierarchyTest.php
index 9d8da92b7..bed077d27 100644
--- a/tests/model/HierarchyTest.php
+++ b/tests/model/HierarchyTest.php
@@ -51,7 +51,27 @@ class HierarchyTest extends SapphireTest {
 		
 		$this->assertEquals(array('Page 2', 'Page 3', 'Page 2a', 'Page 2b'), $marked);
 		$this->assertEquals(array('Page 2', 'Page 2a', 'Page 2b'), $expanded);
+	}
+			
+	function testLoadDescendantIDListInto() {
+		$page2 = $this->objFromFixture('Page', 'page2');
+		$page2a = $this->objFromFixture('Page', 'page2a');
+		$page2b = $this->objFromFixture('Page', 'page2b');
+		$page2aa = $this->objFromFixture('Page', 'page2aa');
+		$page2ab = $this->objFromFixture('Page', 'page2ab');
 		
-	} 
-	
+		$page2IdList = $page2->getDescendantIDList();
+		$page2aIdList = $page2a->getDescendantIDList();
+		
+		$this->assertContains($page2a->ID, $page2IdList);
+		$this->assertContains($page2b->ID, $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);
+		$this->assertEquals(2, count($page2aIdList));
+	}
+
 }
\ No newline at end of file
diff --git a/tests/model/HierarchyTest.yml b/tests/model/HierarchyTest.yml
index 74d94eb70..3254d8db9 100644
--- a/tests/model/HierarchyTest.yml
+++ b/tests/model/HierarchyTest.yml
@@ -17,3 +17,15 @@ Page:
    page3b:
       Parent: =>Page.page3
       Title: Page 3b
+   page2aa:
+      Parent: =>Page.page2a
+      Title: Page 2aa
+   page2ab:
+      Parent: =>Page.page2a
+      Title: Page 2ab
+   page3aa:
+      Parent: =>Page.page3a
+      Title: Page 3aa
+   page3ab:
+      Parent: =>Page.page3a
+      Title: Page 3ab
\ No newline at end of file