diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index ba31f8f..fd81f9b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php-versions: ['8.2', '8.3']
+        php-versions: ['8.3', '8.4']
         dependency-versions: ['lowest', 'highest']
     runs-on: ubuntu-latest
     steps:
diff --git a/composer.json b/composer.json
index 96caa61..0c82f47 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
         "assoconnect/php-quality-config": "^1.16"
     },
     "require": {
-        "php": "^8.2",
+        "php": "^8.3",
         "ext-intl": "*",
         "thecodingmachine/safe": "^3.0"
     },
diff --git a/src/AbsoluteDate.php b/src/AbsoluteDate.php
index 33c8636..6734f6b 100644
--- a/src/AbsoluteDate.php
+++ b/src/AbsoluteDate.php
@@ -180,7 +180,7 @@ public function __toString(): string
      * @param \DateTimeInterface|null $datetime Point in time to find the date from
      * @throws \Exception
      */
-    public static function createInTimezone(DateTimeZone $timezone, \DateTimeInterface $datetime = null): self
+    public static function createInTimezone(DateTimeZone $timezone, ?\DateTimeInterface $datetime = null): self
     {
         return new self(
             (new DateTimeImmutable('@' . (null === $datetime ? time() : $datetime->getTimestamp())))
@@ -195,7 +195,7 @@ public static function createInTimezone(DateTimeZone $timezone, \DateTimeInterfa
      * @param string $relative Relative format to use
      * @param ?DateTimeZone $timezone Timezone to use to get the right date
      */
-    public static function createRelative(string $relative = 'now', DateTimeZone $timezone = null): self
+    public static function createRelative(string $relative = 'now', ?DateTimeZone $timezone = null): self
     {
         if (null === $timezone) {
             $timezone = new DateTimeZone('UTC');