diff --git a/src/DefaultValueBinder.php b/src/DefaultValueBinder.php
index 01346c67..85a0c021 100644
--- a/src/DefaultValueBinder.php
+++ b/src/DefaultValueBinder.php
@@ -12,7 +12,7 @@ class DefaultValueBinder extends PhpSpreadsheetDefaultValueBinder
      * @param  mixed  $value  Value to bind in cell
      * @return bool
      */
-    public function bindValue(Cell $cell, $value)
+    public function bindValue(Cell $cell, mixed $value): bool
     {
         if (is_array($value)) {
             $value = \json_encode($value);