diff --git a/.travis.yml b/.travis.yml
index 402a996..1c59030 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,32 +1,26 @@
 language: php
 
-php:
-# - 5.3 # requires old distro, see below
-  - 5.4
-  - 5.5
-  - 5.6
-  - 7.0
-  - 7.1
-  - 7.2
-  - 7.3
-# - hhvm # requires legacy phpunit & ignore errors, see below
-
 # lock distro so new future defaults will not break the build
 dist: trusty
 
-matrix:
+jobs:
   include:
     - php: 5.3
       dist: precise
-    - php: hhvm
-      install: composer require phpunit/phpunit:^5 --dev --no-interaction
+    - php: 5.4
+    - php: 5.5
+    - php: 5.6
+    - php: 7.0
+    - php: 7.1
+    - php: 7.2
+    - php: 7.3
+    - php: 7.4
+    - php: hhvm-3.18
   allow_failures:
-    - php: hhvm
-
-sudo: false
+    - php: hhvm-3.18
 
 install:
   - composer install --no-interaction
 
 script:
-  - ./vendor/bin/phpunit --coverage-text
+  - vendor/bin/phpunit --coverage-text
diff --git a/composer.json b/composer.json
index a8f4a43..ae9c39f 100644
--- a/composer.json
+++ b/composer.json
@@ -14,6 +14,6 @@
         "psr-4": { "React\\Tests\\Cache\\": "tests/" }
     },
     "require-dev": {
-        "phpunit/phpunit": "^6.4 || ^5.7 || ^4.8.35"
+        "phpunit/phpunit": "^9.0 || ^5.7 || ^4.8.35"
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index d02182f..0e947b8 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,11 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<phpunit colors="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         bootstrap="vendor/autoload.php"
->
+<phpunit bootstrap="vendor/autoload.php" colors="true">
     <testsuites>
         <testsuite name="React Test Suite">
             <directory>./tests/</directory>
diff --git a/tests/ArrayCacheTest.php b/tests/ArrayCacheTest.php
index 3b5bd8c..420d45f 100644
--- a/tests/ArrayCacheTest.php
+++ b/tests/ArrayCacheTest.php
@@ -11,7 +11,10 @@ class ArrayCacheTest extends TestCase
      */
     private $cache;
 
-    public function setUp()
+    /**
+     * @before
+     */
+    public function setUpArrayCache()
     {
         $this->cache = new ArrayCache();
     }
diff --git a/tests/CallableStub.php b/tests/CallableStub.php
deleted file mode 100644
index 2f547cd..0000000
--- a/tests/CallableStub.php
+++ /dev/null
@@ -1,10 +0,0 @@
-<?php
-
-namespace React\Tests\Cache;
-
-class CallableStub
-{
-    public function __invoke()
-    {
-    }
-}
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 5d31a0e..53597e0 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -49,6 +49,12 @@ protected function expectCallableNever()
 
     protected function createCallableMock()
     {
-        return $this->getMockBuilder('React\Tests\Cache\CallableStub')->getMock();
+        if (method_exists('PHPUnit\Framework\MockObject\MockBuilder', 'addMethods')) {
+            // PHPUnit 9+
+            return $this->getMockBuilder('stdClass')->addMethods(array('__invoke'))->getMock();
+        } else {
+            // legacy PHPUnit 4 - PHPUnit 9
+            return $this->getMockBuilder('stdClass')->setMethods(array('__invoke'))->getMock();
+        }
     }
 }