diff --git a/src/PantherTestCaseTrait.php b/src/PantherTestCaseTrait.php
index 76580715..d66667b3 100644
--- a/src/PantherTestCaseTrait.php
+++ b/src/PantherTestCaseTrait.php
@@ -67,7 +67,7 @@ trait PantherTestCaseTrait
         'external_base_uri' => null,
     ];
 
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
         if (self::$stopServerOnTeardown) {
             static::stopWebServer();
diff --git a/tests/ServerExtensionTest.php b/tests/ServerExtensionTest.php
index 59378d09..fbe6febf 100644
--- a/tests/ServerExtensionTest.php
+++ b/tests/ServerExtensionTest.php
@@ -18,7 +18,7 @@
 
 class ServerExtensionTest extends TestCase
 {
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
         PantherTestCase::$stopServerOnTeardown = true;
     }
diff --git a/tests/ServerListenerTest.php b/tests/ServerListenerTest.php
index 54e01d65..643db76d 100644
--- a/tests/ServerListenerTest.php
+++ b/tests/ServerListenerTest.php
@@ -21,7 +21,7 @@
 
 class ServerListenerTest extends TestCase
 {
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
         PantherTestCase::$stopServerOnTeardown = true;
     }
diff --git a/tests/WebDriver/WebDriverMouseTest.php b/tests/WebDriver/WebDriverMouseTest.php
index a9f46406..1184c379 100644
--- a/tests/WebDriver/WebDriverMouseTest.php
+++ b/tests/WebDriver/WebDriverMouseTest.php
@@ -20,7 +20,7 @@
  */
 class WebDriverMouseTest extends TestCase
 {
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
         self::createPantherClient()->request('GET', self::$baseUri.'/mouse.html');
     }