diff --git a/src/Storage/DBFile.php b/src/Storage/DBFile.php
index 5ea53c00..f4984c26 100644
--- a/src/Storage/DBFile.php
+++ b/src/Storage/DBFile.php
@@ -464,9 +464,9 @@ protected function assertFilenameValid(string $filename): void
     /**
      * Hook to validate this record against a validation result
      *
-     * @param string $filename Optional filename to validate. If omitted, the current value is validated.
+     * @param null|string $filename Optional filename to validate. If omitted, the current value is validated.
      */
-    public function validateFilename(ValidationResult $result, $filename = null): bool
+    public function validateFilename(ValidationResult $result, ?string $filename = null): bool
     {
         if (empty($filename)) {
             $filename = $this->getFilename();
@@ -494,7 +494,6 @@ public function setField(string $fieldName, mixed $value, bool $markChanged = tr
         return parent::setField($fieldName, $value, $markChanged);
     }
 
-
     /**
      * Returns the size of the file type in an appropriate format.
      *