diff --git a/library/Icinga/Data/Tree/Node.php b/library/Icinga/Data/Tree/Node.php
index db3a49749..b8f9e8dad 100644
--- a/library/Icinga/Data/Tree/Node.php
+++ b/library/Icinga/Data/Tree/Node.php
@@ -4,24 +4,47 @@
 
 namespace Icinga\Data\Tree;
 
+use Exception;
 use RecursiveIteratorIterator;
 use RuntimeException;
 use SplDoublyLinkedList;
 
 class Node extends SplDoublyLinkedList implements NodeInterface
 {
+    /**
+     * The node's value
+     *
+     * @var mixed
+     */
     protected $value;
 
+    /**
+     * Create a new node
+     *
+     * @param mixed $value The node's value
+     */
     public function __construct($value = null)
     {
         $this->value = $value;
     }
 
+    /**
+     * Get the node's value
+     *
+     * @return mixed
+     */
     public function getValue()
     {
         return $this->value;
     }
 
+    /**
+     * Create a new node from the given value and insert the node as the last child of this node
+     *
+     * @param   mixed           $value  The node's value
+     *
+     * @return  NodeInterface           The appended node
+     */
     public function appendChild($value)
     {
         $child = new static($value);
@@ -29,31 +52,55 @@ class Node extends SplDoublyLinkedList implements NodeInterface
         return $child;
     }
 
+    /**
+     * Whether this node has child nodes
+     *
+     * @return bool
+     */
     public function hasChildren()
     {
         $current = $this->current();
-        if ($current === null) {;
+        if ($current === null) {
             $current = $this;
         }
         return ! $current->isEmpty();
     }
 
+    /**
+     * Get the node's child nodes
+     *
+     * @return NodeInterface
+     */
     public function getChildren()
     {
         $current = $this->current();
-        if ($current === null) {;
+        if ($current === null) {
             $current = $this;
         }
         return $current;
     }
 
+    /**
+     * Find the first child node by searching through nodes deeper than the immediate children using a custom function
+     *
+     * @param   $callback
+     *
+     * @return  NodeInterface|null
+     * @throws  Exception
+     */
     public function findNodeBy($callback)
     {
         if (! is_callable($callback)) {
-            throw new RuntimeException();
+            throw new RuntimeException('Callable expected');
         }
         foreach (new RecursiveIteratorIterator($this, RecursiveIteratorIterator::SELF_FIRST) as $node) {
-            if (call_user_func($callback, $node)) {
+            try {
+                $found = call_user_func($callback, $node);
+            } catch (Exception $e) {
+                // TODO(el): Log exception and return false instead?
+                throw $e;
+            }
+            if ($found) {
                 return $node;
             }
         }
diff --git a/library/Icinga/Data/Tree/NodeInterface.php b/library/Icinga/Data/Tree/NodeInterface.php
index 1d96973e0..6953214dc 100644
--- a/library/Icinga/Data/Tree/NodeInterface.php
+++ b/library/Icinga/Data/Tree/NodeInterface.php
@@ -9,11 +9,11 @@ use RecursiveIterator;
 interface NodeInterface extends RecursiveIterator
 {
     /**
-     * Append a child to the node
+     * Create a new node from the given value and insert the node as the last child of this node
      *
-     * @param   mixed $value
+     * @param   mixed           $value  The node's value
      *
-     * @return  self
+     * @return  NodeInterface           The appended node
      */
     public function appendChild($value);