diff --git a/.github/workflows/phpunit.yml b/.github/workflows/phpunit.yml
index 5bc1cfa..d418c59 100644
--- a/.github/workflows/phpunit.yml
+++ b/.github/workflows/phpunit.yml
@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-versions: [ '7.0', '7.1', '7.2', '7.3', '7.4' ]
+        php-versions: [ '7.3', '7.4', '8.0', '8.1' ]
 
     name: PHP ${{ matrix.php-versions }} Test
 
diff --git a/composer.json b/composer.json
index 526535b..5e8f296 100644
--- a/composer.json
+++ b/composer.json
@@ -24,12 +24,12 @@
     "fetch": "bin/update"
   },
   "require": {
-    "php": ">=7.0",
+    "php": ">=7.3",
     "ext-json": "*",
     "symfony/polyfill-mbstring": "^1.2"
   },
   "require-dev": {
-    "phpunit/phpunit": "6.*|7.*"
+    "phpunit/phpunit": "9.*"
   },
   "autoload": {
     "psr-4": {
diff --git a/tests/Base.php b/tests/Base.php
index 3307d84..41c3717 100644
--- a/tests/Base.php
+++ b/tests/Base.php
@@ -11,7 +11,7 @@ class Base extends TestCase
     protected $isGood = 'Allo';
     protected $looksGood;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->looksGood = str_replace($this->latinA, $this->greekA, $this->isGood);