diff --git a/phpthumb.class.php b/phpthumb.class.php
index 1b3aa79..0bfde8d 100644
--- a/phpthumb.class.php
+++ b/phpthumb.class.php
@@ -314,7 +314,7 @@ public function __destruct() {
 		$this->purgeTempFiles();
 	}
 
-	public function __set(string $name, mixed $value): void {
+	public function __set(string $name, $value): void {
 	}
 
 	// public: