diff --git a/.travis.yml b/.travis.yml
index 16362f20..30be35b8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,12 +1,24 @@
 language: php
 
 php:
-  - 5.3
+# - 5.3 # requires old distro, see below
   - 5.4
   - 5.5
   - 5.6
-  - 7
-  - hhvm
+  - 7.0
+  - 7.1
+  - 7.2
+  - hhvm # ignore errors, see below
+
+# lock distro so future defaults will not break the build
+dist: trusty
+
+matrix:
+  include:
+    - php: 5.3
+      dist: precise
+  allow_failures:
+    - php: hhvm
 
 sudo: false
 
@@ -14,4 +26,4 @@ install:
   - composer install --no-interaction
 
 script:
-  - php vendor/bin/phpunit --coverage-text
+  - vendor/bin/phpunit --coverage-text
diff --git a/README.md b/README.md
index 03ece0c0..31f41e6b 100644
--- a/README.md
+++ b/README.md
@@ -96,16 +96,25 @@ The recommended way to install this library is [through composer](http://getcomp
 }
 ```
 
+This project aims to run on any platform and thus does not require any PHP
+extensions and supports running on legacy PHP 5.3 through current PHP 7+ and
+HHVM.
+It's *highly recommended to use PHP 7+* for this project.
+
 You may also want to install some of the [additional components](#components).
 A list of all official components can be found in the [graphp project](https://github.com/graphp).
 
 ## Tests
 
 This library uses PHPUnit for its extensive test suite.
-You can either use a global installation or rely on the one composer installs
-when you first run `$ composer install`.
-This sets up the developer environment, so that you
-can now run it from the project root directory:
+To run the test suite, you first need to clone this repo and then install all
+dependencies [through Composer](https://getcomposer.org):
+
+```bash
+$ composer install
+```
+
+To run the test suite, go to the project root and run:
 
 ```bash
 $ php vendor/bin/phpunit
diff --git a/_config.yml b/_config.yml
deleted file mode 100644
index c4192631..00000000
--- a/_config.yml
+++ /dev/null
@@ -1 +0,0 @@
-theme: jekyll-theme-cayman
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 61564dd8..f316bb91 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
         "php": "^7.0 || ^5.3"
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.0"
+        "phpunit/phpunit": "^6.4 || ^5.7 || ^4.8.35"
     },
     "suggest": {
         "graphp/graphviz": "GraphViz graph drawing / DOT output",
diff --git a/tests/GraphTest.php b/tests/GraphTest.php
index 45731b13..e72239c8 100644
--- a/tests/GraphTest.php
+++ b/tests/GraphTest.php
@@ -203,7 +203,7 @@ public function testCreateVerticesNone()
     /**
      * expect to fail for invalid number of vertices
      * @expectedException InvalidArgumentException
-     * @dataProvider testCreateVerticesFailProvider
+     * @dataProvider createVerticesFailProvider
      */
     public function testCreateVerticesFail($number)
     {
@@ -211,7 +211,7 @@ public function testCreateVerticesFail($number)
         $graph->createVertices($number);
     }
 
-    public static function testCreateVerticesFailProvider()
+    public static function createVerticesFailProvider()
     {
         return array(
             array(-1),
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 7653cb20..7d739787 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -6,10 +6,9 @@
 use Fhaculty\Graph\Edge\Base as Edge;
 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)
     {
@@ -29,11 +28,8 @@ protected function assertGraphEquals(Graph $expected, Graph $actual)
         // do not use assertVertexEquals() in order to not increase assertion counter
 
         foreach ($expected->getVertices()->getMap() as $vid => $vertex) {
-            try {
-                $other = $actual->getVertex($vid);
-            } catch (Exception $e) {
-                $this->fail();
-            }
+            $other = $actual->getVertex($vid);
+
             if ($this->getVertexDump($vertex) !== $this->getVertexDump($vertex)) {
                 $this->fail();
             }