diff --git a/component/Abstract/Collection.php b/component/Abstract/Collection.php
index 2583c1c..8b4cca7 100644
--- a/component/Abstract/Collection.php
+++ b/component/Abstract/Collection.php
@@ -12,7 +12,7 @@ public function __construct(array $items = [])
 		$this->items = $items;
 	}
 
-	protected function addItem(mixed $item)
+	protected function addItem(mixed $item): self
 	{
 		if (array_search($item, $this->items) == false) {
 			$this->items[] = $item;
@@ -21,7 +21,7 @@ protected function addItem(mixed $item)
 		return $this;
 	}
 
-	protected function removeItem(mixed $item)
+	protected function removeItem(mixed $item): self
 	{
 		if (($key = array_search($item, $this->items)) !== false) {
 			unset($this->items[ $key ]);
@@ -30,7 +30,7 @@ protected function removeItem(mixed $item)
 		return $this;
 	}
 
-	public function itemsIterator()
+	public function itemsIterator(): \Generator
 	{
 		foreach ($this->items as $item) {
 			yield $item;