diff --git a/src/Investigator.php b/src/Investigator.php
index 591a77b..5ec9671 100644
--- a/src/Investigator.php
+++ b/src/Investigator.php
@@ -7,7 +7,7 @@
 trait Investigator
 {
     /**
-     * @param  array<string>  $array
+     * @param  array<string|array<string>>  $array
      * @return array<string>
      */
     private function lowercasesIn(array $array): array