diff --git a/composer.json b/composer.json
index 67060367..e4c58eb2 100644
--- a/composer.json
+++ b/composer.json
@@ -7,7 +7,7 @@
         "php": ">=5.4.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.8"
+        "phpunit/phpunit": "~4.8.35"
     },
     "suggest": {
         "ext-libevent": ">=0.1.0 for LibEventLoop and PHP5 only",
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 0bc26a40..dbdd54ce 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -2,9 +2,10 @@
 
 namespace React\Tests\EventLoop;
 
+use PHPUnit\Framework\TestCase as BaseTestCase;
 use React\EventLoop\LoopInterface;
 
-class TestCase extends \PHPUnit_Framework_TestCase
+class TestCase extends BaseTestCase
 {
     protected function expectCallableExactly($amount)
     {