diff --git a/e107_handlers/model_class.php b/e107_handlers/model_class.php
index e356a8c252..ea99d50a31 100755
--- a/e107_handlers/model_class.php
+++ b/e107_handlers/model_class.php
@@ -3519,7 +3519,7 @@ protected static function flattenTree($tree, $sort_field = null, $sort_order = 1
 
 		foreach($tree as $item)
 		{
-			$children = $item['_children'];
+			$children = isset($item['_children']) ? $item['_children'] : null;
 			unset($item['_children']);
 			$item['_depth'] = $depth;
 			if($depth > 0)
diff --git a/e107_tests/tests/unit/TreeModelTest.php b/e107_tests/tests/unit/TreeModelTest.php
index 1fce4cf4ba..e4e4da4f7f 100644
--- a/e107_tests/tests/unit/TreeModelTest.php
+++ b/e107_tests/tests/unit/TreeModelTest.php
@@ -52,11 +52,11 @@ public function testTreeParentsAreAssignedCorrectly()
     {
         $key = $this->sample_key;
         $parent_key = $this->sample_parent_key;
-        $l0_id     = $this->tree[1][$key];
-        $l1_id     = $this->tree[1]['_children'][0][$key];
-        $l1_parent = $this->tree[1]['_children'][0][$parent_key];
-        $l2_id     = $this->tree[1]['_children'][0]['_children'][0][$key];
-        $l2_parent = $this->tree[1]['_children'][0]['_children'][0][$parent_key];
+        $l0_id     = $this->tree[0][$key];
+        $l1_id     = $this->tree[0]['_children'][0][$key];
+        $l1_parent = $this->tree[0]['_children'][0][$parent_key];
+        $l2_id     = $this->tree[0]['_children'][0]['_children'][0][$key];
+        $l2_parent = $this->tree[0]['_children'][0]['_children'][0][$parent_key];
 
         $this->assertEquals($l0_id, $l1_parent);
         $this->assertEquals($l1_id, $l2_parent);