diff --git a/.travis.yml b/.travis.yml
index 16362f20..05d0c1ea 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,6 @@
 language: php
 
 php:
-  - 5.3
   - 5.4
   - 5.5
   - 5.6
@@ -10,6 +9,11 @@ php:
 
 sudo: false
 
+matrix:
+    include:
+        - php: 5.3
+          dist: precise
+
 install:
   - composer install --no-interaction
 
diff --git a/composer.json b/composer.json
index 61564dd8..24ca257f 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
         "php": "^7.0 || ^5.3"
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.0"
+        "phpunit/phpunit": "~4.8.35 || ~5.7 || ~6.4"
     },
     "suggest": {
         "graphp/graphviz": "GraphViz graph drawing / DOT output",
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 7653cb20..48e6bd7a 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -7,9 +7,9 @@
 use Fhaculty\Graph\Graph;
 use Fhaculty\Graph\Vertex;
 use Fhaculty\Graph\Set\Vertices;
-use PHPUnit_Framework_TestCase;
+use PHPUnit\Framework\TestCase as BaseTestCase;
 
-class TestCase extends PHPUnit_Framework_TestCase
+class TestCase extends BaseTestCase
 {
     protected function assertGraphEquals(Graph $expected, Graph $actual)
     {