diff --git a/.github/workflows/test-php.yml b/.github/workflows/test-php.yml
index f1d64ee0..417d580f 100755
--- a/.github/workflows/test-php.yml
+++ b/.github/workflows/test-php.yml
@@ -13,7 +13,7 @@ jobs:
       - name: Setup PHP version
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '7.2'
+          php-version: '7.4'
           extensions: simplexml
       - name: Checkout source code
         uses: actions/checkout@v2
@@ -49,7 +49,7 @@ jobs:
       - name: Setup PHP version
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '7.2'
+          php-version: '7.4'
           extensions: simplexml, mysql
           tools: phpunit-polyfills
       - name: Checkout source code
diff --git a/tests/test-ajax.php b/tests/test-ajax.php
index a7bd7a6b..11fb3396 100644
--- a/tests/test-ajax.php
+++ b/tests/test-ajax.php
@@ -37,7 +37,7 @@ class Test_Visualizer_Ajax extends WP_Ajax_UnitTestCase {
 	/**
 	 * Set up.
 	 */
-	public function setUp() {
+	public function setUp(): void {
 		parent::setUp();
 		$this->admin_user_id = $this->factory->user->create(
 			array(