diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6df7572..1980d8e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -18,6 +18,7 @@ jobs:
                     -   php: "8.1"
                     -   php: "8.2"
                     -   php: "8.3"
+                    -   php: "8.4"
         steps:
             -   name: Checkout source
                 uses: actions/checkout@v4
diff --git a/src/ExecutionException.php b/src/ExecutionException.php
index 64517e8..89a941b 100644
--- a/src/ExecutionException.php
+++ b/src/ExecutionException.php
@@ -20,7 +20,7 @@ final class ExecutionException extends \RuntimeException
      */
     private $result;
 
-    public function __construct(CliResult $result, $message = '', $code = 0, \Exception $previous = null)
+    public function __construct(CliResult $result, $message = '', $code = 0, ?\Exception $previous = null)
     {
         parent::__construct($message, $code, $previous);
 
diff --git a/src/ScriptExecutor.php b/src/ScriptExecutor.php
index 36c873b..da61f47 100644
--- a/src/ScriptExecutor.php
+++ b/src/ScriptExecutor.php
@@ -51,7 +51,7 @@ final class ScriptExecutor
      * @param string[]  $scriptParts
      * @param ?string[] $scriptInit
      */
-    public function __construct(array $scriptParts, string $cwd, array $scriptInit = null)
+    public function __construct(array $scriptParts, string $cwd, ?array $scriptInit = null)
     {
         $this->scriptParts = $scriptParts;
         $this->cwd = $cwd;
@@ -69,7 +69,7 @@ public function __destruct()
      * @param string[]  $scriptParts
      * @param ?string[] $scriptInit
      */
-    public static function create(array $scriptParts, string $cwd, array $scriptInit = null): self
+    public static function create(array $scriptParts, string $cwd, ?array $scriptInit = null): self
     {
         return new self($scriptParts, $cwd, $scriptInit);
     }