diff --git a/src/Framework/Config/GacelaConfigBuilder/AppConfigBuilder.php b/src/Framework/Config/GacelaConfigBuilder/AppConfigBuilder.php
index b39fe6c4..733b974d 100644
--- a/src/Framework/Config/GacelaConfigBuilder/AppConfigBuilder.php
+++ b/src/Framework/Config/GacelaConfigBuilder/AppConfigBuilder.php
@@ -20,7 +20,7 @@ final class AppConfigBuilder
      * @param string $pathLocal define the path where Gacela will read the local config file
      * @param class-string<ConfigReaderInterface>|ConfigReaderInterface|null $reader Define the reader class which will read and parse the config files
      */
-    public function add(string $path, string $pathLocal = '', string|ConfigReaderInterface $reader = null): self
+    public function add(string $path, string $pathLocal = '', string|ConfigReaderInterface|null $reader = null): self
     {
         $readerInstance = $this->normalizeReader($reader);
 
diff --git a/src/Framework/Gacela.php b/src/Framework/Gacela.php
index 77d3963b..58e34660 100644
--- a/src/Framework/Gacela.php
+++ b/src/Framework/Gacela.php
@@ -105,7 +105,7 @@ public static function overrideExistingResolvedClass(string $className, object $
     /**
      * @param  null|Closure(GacelaConfig):void  $configFn
      */
-    private static function processConfigFnIntoSetup(Closure $configFn = null): SetupGacelaInterface
+    private static function processConfigFnIntoSetup(?Closure $configFn = null): SetupGacelaInterface
     {
         if ($configFn instanceof Closure) {
             return SetupGacela::fromCallable($configFn);