diff --git a/includes/Container.php b/includes/Container.php
index b5bdcb0..6f4c706 100644
--- a/includes/Container.php
+++ b/includes/Container.php
@@ -415,7 +415,7 @@ public function rewind(): void {
 	 *
 	 * @return bool True on success or false on failure.
 	 */
-	public function offsetExists( mixed $offset ): mixed {
+	public function offsetExists( mixed $offset ): bool {
 		return $this->has( $offset );
 	}