diff --git a/src/Functions/NoParameterWithNullDefaultValueRule.php b/src/Functions/NoParameterWithNullDefaultValueRule.php
index fdf6e76a..fae24d23 100644
--- a/src/Functions/NoParameterWithNullDefaultValueRule.php
+++ b/src/Functions/NoParameterWithNullDefaultValueRule.php
@@ -37,11 +37,7 @@ public function processNode(
         }
 
         $params = \array_filter($node->params, static function (Node\Param $node): bool {
-            if (!$node->default instanceof Node\Expr\ConstFetch) {
-                return false;
-            }
-
-            return 'null' === $node->default->name->toLowerString();
+            return self::hasNullDefaultValue($node);
         });
 
         if (0 === \count($params)) {
@@ -68,4 +64,13 @@ public function processNode(
                 ->build();
         }, $params));
     }
+
+    private static function hasNullDefaultValue(Node\Param $node): bool
+    {
+        if (!$node->default instanceof Node\Expr\ConstFetch) {
+            return false;
+        }
+
+        return 'null' === $node->default->name->toLowerString();
+    }
 }