diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2333f1e..6e4fc81 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,7 +8,7 @@ jobs:
     if: "!contains(github.event.head_commit.message, '[ci skip]')"
     strategy:
       matrix:
-        php: ['8.1', '8.2', '8.3']
+        php: ['8.2', '8.3']
     name: PHP ${{ matrix.php }}
     steps:
     - uses: actions/checkout@v3
diff --git a/composer.json b/composer.json
index a9cedea..673731d 100644
--- a/composer.json
+++ b/composer.json
@@ -4,7 +4,7 @@
     "type": "library",
     "license": "LGPL-3.0",
     "require": {
-        "php": "^8.1",
+        "php": "^8.2",
         "php-64bit": "*"
     },
     "require-dev": {
diff --git a/src/Vector3.php b/src/Vector3.php
index ea0d140..11a6484 100644
--- a/src/Vector3.php
+++ b/src/Vector3.php
@@ -33,7 +33,7 @@
 use function sqrt;
 use const PHP_ROUND_HALF_UP;
 
-class Vector3{
+readonly class Vector3{
 	public function __construct(
 		public float|int $x,
 		public float|int $y,