diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 34b2a0b..4ed432e 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -6,7 +6,7 @@ jobs:
     strategy:
       matrix:
         operating-system: [ubuntu-latest]
-        php-versions: ['7.3', '7.4', '8.0']
+        php-versions: ['8.0', '8.1', '8.2']
     name: PHP ${{ matrix.php-versions }} Test on ${{ matrix.operating-system }}
     steps:
     - name: Checkout
diff --git a/composer.json b/composer.json
index 35f4f6e..7ffb8a2 100644
--- a/composer.json
+++ b/composer.json
@@ -9,7 +9,7 @@
     "search engine"
   ],
   "require": {
-    "php": "^7.3|^8.0"
+    "php": "^8.0"
   },
   "require-dev": {
     "phpunit/phpunit": "^7.0|^9.0",
diff --git a/src/Commands/Command.php b/src/Commands/Command.php
index e3a32fa..b8f3991 100644
--- a/src/Commands/Command.php
+++ b/src/Commands/Command.php
@@ -6,10 +6,16 @@
 
 abstract class Command implements CommandInterface
 {
-    private $command;
-    private $parameters;
+    private string $command;
+    /**
+     * @var array<mixed>
+     */
+    private array $parameters;
 
-    public function __construct($command, $parameters = [])
+    /**
+     * @param array<mixed> $parameters
+     */
+    public function __construct(string $command, array $parameters = [])
     {
         $this->command = $command;
         $this->parameters = $parameters;
@@ -18,8 +24,9 @@ public function __construct($command, $parameters = [])
     /**
      * Wrap the string in quotes, and normalize whitespace. Also remove double quotes.
      */
-    protected function wrapInQuotes($string)
+    protected function wrapInQuotes(string $string):string
     {
+        /** @var string $string */
         $string = preg_replace('/[\r\n\t"]/', ' ', $string);
         $string = '"' . str_replace('"', '\"', $string) . '"';
         return $string;