diff --git a/.travis.yml b/.travis.yml
index 242d3afc..2a1ab599 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,6 +8,7 @@ php:
   - 7.1
   - 7.2
   - 7.3
+  - 7.4
   - nightly
 
 matrix:
diff --git a/composer.json b/composer.json
index 7ba634cb..873c5640 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,7 @@
     "php": ">=5.5.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "^4.0 || ^5.0",
+    "phpunit/phpunit": "^4.8.36 || ^5.0",
     "guzzlehttp/guzzle": "^6.0",
     "doctrine/cache": "^1.0",
     "league/flysystem": "^1.0",
diff --git a/tests/BaseTest.php b/tests/BaseTest.php
index f1516f7a..803037fa 100644
--- a/tests/BaseTest.php
+++ b/tests/BaseTest.php
@@ -9,15 +9,16 @@
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\CacheMiddleware;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
-class BaseTest extends \PHPUnit_Framework_TestCase
+class BaseTest extends TestCase
 {
     /**
      * @var Client
      */
     protected $client;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/DelegatingCacheTest.php b/tests/DelegatingCacheTest.php
index 5112ebbc..da1322b6 100644
--- a/tests/DelegatingCacheTest.php
+++ b/tests/DelegatingCacheTest.php
@@ -28,7 +28,7 @@ class DelegatingCacheTest extends TestCase
      */
     protected $stack;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $this->stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/GreedyCacheTest.php b/tests/GreedyCacheTest.php
index d3f05d9c..f26b8257 100644
--- a/tests/GreedyCacheTest.php
+++ b/tests/GreedyCacheTest.php
@@ -12,8 +12,9 @@
 use Kevinrob\GuzzleCache\KeyValueHttpHeader;
 use Kevinrob\GuzzleCache\Strategy\GreedyCacheStrategy;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
-class GreedyCacheTest extends \PHPUnit_Framework_TestCase
+class GreedyCacheTest extends TestCase
 {
     /**
      * @var Client
diff --git a/tests/HeaderExpireTest.php b/tests/HeaderExpireTest.php
index f6955719..ace2f3ae 100644
--- a/tests/HeaderExpireTest.php
+++ b/tests/HeaderExpireTest.php
@@ -8,6 +8,7 @@
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\CacheMiddleware;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
 /**
  * Created by IntelliJ IDEA.
@@ -15,7 +16,7 @@
  * Date: 29.06.2015
  * Time: 22:48.
  */
-class HeaderExpireTest extends \PHPUnit_Framework_TestCase
+class HeaderExpireTest extends TestCase
 {
     /**
      * @var Client
@@ -27,7 +28,7 @@ class HeaderExpireTest extends \PHPUnit_Framework_TestCase
      */
     protected $sendError = false;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/InvalidateCacheTest.php b/tests/InvalidateCacheTest.php
index 690eaf13..1b6ac576 100644
--- a/tests/InvalidateCacheTest.php
+++ b/tests/InvalidateCacheTest.php
@@ -7,15 +7,16 @@
 use GuzzleHttp\Promise\FulfilledPromise;
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\CacheMiddleware;
+use PHPUnit\Framework\TestCase;
 
-class InvalidateCacheTest extends \PHPUnit_Framework_TestCase
+class InvalidateCacheTest extends TestCase
 {
     /**
      * @var Client
      */
     protected $client;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function () {
diff --git a/tests/KeyValueHttpHeaderTest.php b/tests/KeyValueHttpHeaderTest.php
index d31a8140..9c3ddddb 100644
--- a/tests/KeyValueHttpHeaderTest.php
+++ b/tests/KeyValueHttpHeaderTest.php
@@ -10,8 +10,9 @@
 
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\KeyValueHttpHeader;
+use PHPUnit\Framework\TestCase;
 
-class KeyValueHttpHeaderTest extends \PHPUnit_Framework_TestCase
+class KeyValueHttpHeaderTest extends TestCase
 {
     public function testBase()
     {
diff --git a/tests/PrivateCacheTest.php b/tests/PrivateCacheTest.php
index c66092f7..5be441fc 100644
--- a/tests/PrivateCacheTest.php
+++ b/tests/PrivateCacheTest.php
@@ -19,8 +19,9 @@
 use Kevinrob\GuzzleCache\Storage\VolatileRuntimeStorage;
 use Kevinrob\GuzzleCache\Strategy\PrivateCacheStrategy;
 use League\Flysystem\Adapter\Local;
+use PHPUnit\Framework\TestCase;
 
-class PrivateCacheTest extends \PHPUnit_Framework_TestCase
+class PrivateCacheTest extends TestCase
 {
     public function testCacheProvider()
     {
diff --git a/tests/PublicCacheTest.php b/tests/PublicCacheTest.php
index 55ca648d..b3e92719 100644
--- a/tests/PublicCacheTest.php
+++ b/tests/PublicCacheTest.php
@@ -24,15 +24,16 @@
 use Kevinrob\GuzzleCache\Strategy\PublicCacheStrategy;
 use League\Flysystem\Adapter\Local;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
-class PublicCacheTest extends \PHPUnit_Framework_TestCase
+class PublicCacheTest extends TestCase
 {
     /**
      * @var Client
      */
     protected $client;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/RequestCacheControlTest.php b/tests/RequestCacheControlTest.php
index f381c034..2370a151 100644
--- a/tests/RequestCacheControlTest.php
+++ b/tests/RequestCacheControlTest.php
@@ -8,15 +8,16 @@
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\CacheMiddleware;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
-class RequestCacheControlTest extends \PHPUnit_Framework_TestCase
+class RequestCacheControlTest extends TestCase
 {
     /**
      * @var Client
      */
     protected $client;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/ResponseAgeTest.php b/tests/ResponseAgeTest.php
index 87fb3b80..b5950f83 100644
--- a/tests/ResponseAgeTest.php
+++ b/tests/ResponseAgeTest.php
@@ -8,15 +8,16 @@
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\CacheMiddleware;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
-class ResponseAgeTest extends \PHPUnit_Framework_TestCase
+class ResponseAgeTest extends TestCase
 {
     /**
      * @var Client
      */
     protected $client;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/ResponseCacheControlTest.php b/tests/ResponseCacheControlTest.php
index 9be2907e..55bbf186 100644
--- a/tests/ResponseCacheControlTest.php
+++ b/tests/ResponseCacheControlTest.php
@@ -8,15 +8,16 @@
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\CacheMiddleware;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
-class ResponseCacheControlTest extends \PHPUnit_Framework_TestCase
+class ResponseCacheControlTest extends TestCase
 {
     /**
      * @var Client
      */
     protected $client;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/ResponseVaryTest.php b/tests/ResponseVaryTest.php
index 472e3f85..2d5c3032 100644
--- a/tests/ResponseVaryTest.php
+++ b/tests/ResponseVaryTest.php
@@ -8,15 +8,16 @@
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\CacheMiddleware;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
-class ResponseVaryTest extends \PHPUnit_Framework_TestCase
+class ResponseVaryTest extends TestCase
 {
     /**
      * @var Client
      */
     protected $client;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/Strategy/GreedyCacheStrategyTest.php b/tests/Strategy/GreedyCacheStrategyTest.php
index 77b46472..67d1ea9c 100644
--- a/tests/Strategy/GreedyCacheStrategyTest.php
+++ b/tests/Strategy/GreedyCacheStrategyTest.php
@@ -10,15 +10,16 @@
 use Kevinrob\GuzzleCache\CacheMiddleware;
 use Kevinrob\GuzzleCache\Storage\VolatileRuntimeStorage;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
-class GreedyCacheStrategyTest extends \PHPUnit_Framework_TestCase
+class GreedyCacheStrategyTest extends TestCase
 {
     /**
      * @var Client
      */
     protected $client;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {
diff --git a/tests/ValidationTest.php b/tests/ValidationTest.php
index 184fa3af..a10dfdd1 100644
--- a/tests/ValidationTest.php
+++ b/tests/ValidationTest.php
@@ -8,6 +8,7 @@
 use GuzzleHttp\Psr7\Response;
 use Kevinrob\GuzzleCache\CacheMiddleware;
 use Psr\Http\Message\RequestInterface;
+use PHPUnit\Framework\TestCase;
 
 /**
  * Created by IntelliJ IDEA.
@@ -15,7 +16,7 @@
  * Date: 30.06.2015
  * Time: 12:58.
  */
-class ValidationTest extends \PHPUnit_Framework_TestCase
+class ValidationTest extends TestCase
 {
     /**
      * @var Client
@@ -27,7 +28,7 @@ class ValidationTest extends \PHPUnit_Framework_TestCase
      */
     protected $cache;
 
-    public function setUp()
+    protected function setUp()
     {
         // Create default HandlerStack
         $stack = HandlerStack::create(function (RequestInterface $request, array $options) {