diff --git a/src/Y23/Day1.php b/src/Y23/Day1.php
index fb944f0..8e78783 100644
--- a/src/Y23/Day1.php
+++ b/src/Y23/Day1.php
@@ -9,7 +9,7 @@ final class Day1 extends Solution
     /**
      * @var array<string,int>
      */
-    private const NUMBER_STRING = [
+    private const array NUMBER_STRING = [
         'one' => 1,
         'two' => 2,
         'three' => 3,