diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index f51c498..48910a0 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -10,14 +10,14 @@ jobs:
 
     strategy:
       matrix:
-        php-versions: ['8.0', '8.1', '8.2']
+        php-versions: ['8.0', '8.1', '8.2', '8.3']
     steps:
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php-versions }}
           tools: composer:v2
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: php-actions/composer@v6
         with:
           php_version: ${{ matrix.php-versions }}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6bd33db..101069a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Added
 - add dependabot
+- add tests on PHP 8.3
 
 ### Removed
 - remove sensiolabs/security-checker from direct dependency
diff --git a/src/SwisstopoConverter.php b/src/SwisstopoConverter.php
index 9c97d28..1952ef5 100644
--- a/src/SwisstopoConverter.php
+++ b/src/SwisstopoConverter.php
@@ -21,8 +21,8 @@ class SwisstopoConverter
     public static function fromMN95ToWGS(float|int $east, float|int $north): array
     {
         return [
-          'lat' => self::fromMN95ToWGSLatitude($east, $north),
-          'long' => self::fromMN95ToWGSLongitude($east, $north),
+            'lat' => self::fromMN95ToWGSLatitude($east, $north),
+            'long' => self::fromMN95ToWGSLongitude($east, $north),
         ];
     }
 
@@ -40,8 +40,8 @@ public static function fromMN95ToWGS(float|int $east, float|int $north): array
     public static function fromWGSToMN95(float $lat, float $long): array
     {
         return [
-          'east' => self::fromWGSToMN95East($lat, $long),
-          'north' => self::fromWGSToMN95North($lat, $long),
+            'east' => self::fromWGSToMN95East($lat, $long),
+            'north' => self::fromWGSToMN95North($lat, $long),
         ];
     }
 
@@ -59,8 +59,8 @@ public static function fromWGSToMN95(float $lat, float $long): array
     public static function fromMN03ToWGS(int $y, int $x): array
     {
         return [
-          'lat' => self::fromMN03ToWGSLatitude($y, $x),
-          'long' => self::fromMN03ToWGSLongitude($y, $x),
+            'lat' => self::fromMN03ToWGSLatitude($y, $x),
+            'long' => self::fromMN03ToWGSLongitude($y, $x),
         ];
     }
 
@@ -78,8 +78,8 @@ public static function fromMN03ToWGS(int $y, int $x): array
     public static function fromWGSToMN03(float $lat, float $long): array
     {
         return [
-          'x' => self::fromWGSToMN03x($lat, $long),
-          'y' => self::fromWGSToMN03y($lat, $long),
+            'x' => self::fromWGSToMN03x($lat, $long),
+            'y' => self::fromWGSToMN03y($lat, $long),
         ];
     }