diff --git a/.travis.yml b/.travis.yml
index bcbe642f..da0fcd0d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,9 @@ php:
   - 5.6
   - 7.0
   - 7.1
+  - 7.2
+  - 7.3
+  - 7.4
   - nightly # ignore errors, see below
   - hhvm # ignore errors, see below
 
diff --git a/composer.json b/composer.json
index 2fc48091..b3e723a7 100644
--- a/composer.json
+++ b/composer.json
@@ -9,7 +9,7 @@
         "php": ">=5.4.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.8"
+        "phpunit/phpunit": "^7.0 || ^6.5 || ^5.7 || ^4.8.36"
     },
     "autoload": {
         "psr-4": {
@@ -19,7 +19,7 @@
     },
     "autoload-dev": {
         "psr-4": {
-            "React\\Promise\\": "tests/fixtures"
+            "React\\Promise\\": ["tests", "tests/fixtures"]
         }
     },
     "keywords": [
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index b9a689d7..3d184322 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -8,8 +8,7 @@
          convertWarningsToExceptions="true"
          processIsolation="false"
          stopOnFailure="false"
-         syntaxCheck="false"
-         bootstrap="tests/bootstrap.php"
+         bootstrap="vendor/autoload.php"
 >
     <testsuites>
         <testsuite name="Promise Test Suite">
diff --git a/tests/DeferredTest.php b/tests/DeferredTest.php
index 8ee40b8a..b11199b8 100644
--- a/tests/DeferredTest.php
+++ b/tests/DeferredTest.php
@@ -44,6 +44,8 @@ public function progressIsAnAliasForNotify()
     public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerRejectsWithException()
     {
         gc_collect_cycles();
+        gc_collect_cycles(); // clear twice to avoid leftovers in PHP 7.4 with ext-xdebug and code coverage turned on
+
         $deferred = new Deferred(function ($resolve, $reject) {
             $reject(new \Exception('foo'));
         });
@@ -57,6 +59,8 @@ public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerRejectsWithEx
     public function shouldRejectWithoutCreatingGarbageCyclesIfParentCancellerRejectsWithException()
     {
         gc_collect_cycles();
+        gc_collect_cycles(); // clear twice to avoid leftovers in PHP 7.4 with ext-xdebug and code coverage turned on
+
         $deferred = new Deferred(function ($resolve, $reject) {
             $reject(new \Exception('foo'));
         });
diff --git a/tests/FulfilledPromiseTest.php b/tests/FulfilledPromiseTest.php
index f5a2da80..d814c2a2 100644
--- a/tests/FulfilledPromiseTest.php
+++ b/tests/FulfilledPromiseTest.php
@@ -52,6 +52,8 @@ public function shouldThrowExceptionIfConstructedWithAPromise()
     public function shouldNotLeaveGarbageCyclesWhenRemovingLastReferenceToFulfilledPromiseWithAlwaysFollowers()
     {
         gc_collect_cycles();
+        gc_collect_cycles(); // clear twice to avoid leftovers in PHP 7.4 with ext-xdebug and code coverage turned on
+
         $promise = new FulfilledPromise(1);
         $promise->always(function () {
             throw new \RuntimeException();
diff --git a/tests/PromiseTest.php b/tests/PromiseTest.php
index 344b4114..4778129f 100644
--- a/tests/PromiseTest.php
+++ b/tests/PromiseTest.php
@@ -52,6 +52,8 @@ public function shouldRejectIfResolverThrowsException()
     public function shouldResolveWithoutCreatingGarbageCyclesIfResolverResolvesWithException()
     {
         gc_collect_cycles();
+        gc_collect_cycles(); // clear twice to avoid leftovers in PHP 7.4 with ext-xdebug and code coverage turned on
+
         $promise = new Promise(function ($resolve) {
             $resolve(new \Exception('foo'));
         });
diff --git a/tests/Stub/CallableStub.php b/tests/Stub/CallableStub.php
deleted file mode 100644
index 01208933..00000000
--- a/tests/Stub/CallableStub.php
+++ /dev/null
@@ -1,10 +0,0 @@
-<?php
-
-namespace React\Promise\Stub;
-
-class CallableStub
-{
-    public function __invoke()
-    {
-    }
-}
diff --git a/tests/TestCase.php b/tests/TestCase.php
index c9274f44..542629bb 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -2,7 +2,7 @@
 
 namespace React\Promise;
 
-class TestCase extends \PHPUnit_Framework_TestCase
+class TestCase extends \PHPUnit\Framework\TestCase
 {
     public function expectCallableExactly($amount)
     {
@@ -36,8 +36,23 @@ public function expectCallableNever()
 
     public function createCallableMock()
     {
-        return $this
-            ->getMockBuilder('React\\Promise\Stub\CallableStub')
-            ->getMock();
+        return $this->getMockBuilder('stdClass')->setMethods(array('__invoke'))->getMock();
+    }
+
+    public function setExpectedException($exception, $exceptionMessage = '', $exceptionCode = null)
+    {
+        if (method_exists($this, 'expectException')) {
+            // PHPUnit 5+
+            $this->expectException($exception);
+            if ($exceptionMessage !== '') {
+                $this->expectExceptionMessage($exceptionMessage);
+            }
+            if ($exceptionCode !== null) {
+                $this->expectExceptionCode($exceptionCode);
+            }
+        } else {
+            // legacy PHPUnit 4
+            parent::setExpectedException($exception, $exceptionMessage, $exceptionCode);
+        }
     }
 }
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
deleted file mode 100644
index 9b7f872a..00000000
--- a/tests/bootstrap.php
+++ /dev/null
@@ -1,7 +0,0 @@
-<?php
-
-$loader = @include __DIR__.'/../vendor/autoload.php';
-if (!$loader) {
-    $loader = require __DIR__.'/../../../../vendor/autoload.php';
-}
-$loader->addPsr4('React\\Promise\\', __DIR__);