diff --git a/library/Icinga/Data/Tree/TreeNodeIterator.php b/library/Icinga/Data/Tree/TreeNodeIterator.php
index dcba0f1e9..839b1a1d0 100644
--- a/library/Icinga/Data/Tree/TreeNodeIterator.php
+++ b/library/Icinga/Data/Tree/TreeNodeIterator.php
@@ -92,6 +92,6 @@ class TreeNodeIterator implements RecursiveIterator
      */
     public function isEmpty()
     {
-        return empty($this->children);
+        return ! $this->children->count();
     }
 }