diff --git a/composer.json b/composer.json
index e9d299a..5592c32 100644
--- a/composer.json
+++ b/composer.json
@@ -14,8 +14,8 @@
         "http-interop/http-server-middleware": "^1.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^5.7",
-        "eloquent/phony": "^0.14.3",
+        "phpunit/phpunit": "^6.0",
+        "eloquent/phony-phpunit": "^3.0",
         "eloquent/liberator": "^2.0"
     },
     "autoload": {
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 1991041..b70dc03 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -5,11 +5,11 @@
 use Eloquent\Phony\Mock\Handle\InstanceHandle;
 use Eloquent\Phony\Phpunit\Phony;
 use Interop\Http\Server\MiddlewareInterface;
-use PHPUnit_Framework_TestCase;
+use PHPUnit\Framework\TestCase as AbstractTestCase;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 
-abstract class TestCase extends PHPUnit_Framework_TestCase
+abstract class TestCase extends AbstractTestCase
 {
     /**
      * @return ServerRequestInterface