diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
index 5f09a0c..b8b7aac 100644
--- a/.php-cs-fixer.php
+++ b/.php-cs-fixer.php
@@ -22,6 +22,7 @@ return (new PhpCsFixer\Config())
         'ordered_imports' => true,
         'php_unit_strict' => false,
         'phpdoc_order' => true,
+        'phpdoc_to_param_type' => true,
         // 'psr4' => true,
         'strict_comparison' => true,
         'strict_param' => true,
diff --git a/src/Readability.php b/src/Readability.php
index 9c1b983..0bc2ec8 100644
--- a/src/Readability.php
+++ b/src/Readability.php
@@ -546,12 +546,8 @@ class Readability implements LoggerAwareInterface
     /**
      * Get the inner text of a node.
      * This also strips out any excess whitespace to be found.
-     *
-     * @param \DOMElement $e
-     * @param bool        $normalizeSpaces (default: true)
-     * @param bool        $flattenLines    (default: false)
      */
-    public function getInnerText($e, bool $normalizeSpaces = true, bool $flattenLines = false): string
+    public function getInnerText(?\DOMNode $e, bool $normalizeSpaces = true, bool $flattenLines = false): string
     {
         if (null === $e || !isset($e->textContent) || '' === $e->textContent) {
             return '';