diff --git a/src/NodeTrait.php b/src/NodeTrait.php
index b921984..fcca698 100644
--- a/src/NodeTrait.php
+++ b/src/NodeTrait.php
@@ -224,7 +224,7 @@ public function refreshNode()
      *
      * @return BelongsTo
      */
-    public function parent()
+    public function parent() : BelongsTo
     {
         return $this->belongsTo(get_class($this), $this->getParentIdName())
             ->setModel($this);
@@ -235,7 +235,7 @@ public function parent()
      *
      * @return HasMany
      */
-    public function children()
+    public function children() : HasMany
     {
         return $this->hasMany(get_class($this), $this->getParentIdName())
             ->setModel($this);