diff --git a/.github/workflows/push.yml b/.github/workflows/push.yml
index 98d0624..0c8737c 100644
--- a/.github/workflows/push.yml
+++ b/.github/workflows/push.yml
@@ -2,12 +2,21 @@ on: push
 name: Test
 jobs:
   test:
-    name: PHP Linter
+    name: Test
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php: [ '7.4', '8.0', '8.1', '8.2' ]
 
     steps:
       - uses: actions/checkout@master
 
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: none
+
       - name: Run PHP Lint
         run: "find src/ -name '*.php' | xargs -n1 php -l"
 
diff --git a/composer.json b/composer.json
index 1ef8d6f..cdda3a8 100644
--- a/composer.json
+++ b/composer.json
@@ -14,10 +14,10 @@
         "sort-packages": true
     },
     "require": {
-        "php": ">=7.1"
+        "php": "^7.4||^8.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~7.0"
+        "phpunit/phpunit": "~8.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/ForbidsSerialization.php b/src/ForbidsSerialization.php
index e7bf8d7..36dfdbd 100644
--- a/src/ForbidsSerialization.php
+++ b/src/ForbidsSerialization.php
@@ -59,7 +59,7 @@ final public function __wakeup()
      *
      * @throws SerializationForbiddenException always.
      */
-    final public function __serialize()
+    final public function __serialize(): array
     {
         throw new SerializationForbiddenException(get_class($this));
     }
@@ -75,7 +75,7 @@ final public function __serialize()
      *
      * @throws SerializationForbiddenException always.
      */
-    final public function __unserialize()
+    final public function __unserialize(array $data): void
     {
         throw new SerializationForbiddenException(get_class($this));
     }