diff --git a/.travis.yml b/.travis.yml
index 649fb3f..af8a897 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,15 +1,9 @@
 language: php
 dist: trusty
 php:
-  - "5.4"
-  - "5.5"
-  - "5.6"
-  - "7.0"
-  - "7.1"
-matrix:
-  include:
-    - php: "5.3"
-      dist: precise
+  - "7.2"
+  - "7.3"
+  - "7.4"
 install:
   - composer install
 script:
diff --git a/composer.json b/composer.json
index 11848ba..71839a0 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
   },
   "require-dev": {
     "composer/composer": "^2.0",
-    "phpunit/phpunit": "4.*",
+    "phpunit/phpunit": "^8.5.9",
     "derhasi/tempdirectory": "0.1.*",
     "squizlabs/php_codesniffer": "2.*",
     "escapestudios/symfony2-coding-standard": "2.*"
diff --git a/tests/FixturesTest.php b/tests/FixturesTest.php
index c36bcbc..90aa72c 100644
--- a/tests/FixturesTest.php
+++ b/tests/FixturesTest.php
@@ -3,11 +3,12 @@
 namespace DrupalComposer\PreservePaths\Tests;
 
 use derhasi\tempdirectory\TempDirectory;
+use PHPUnit\Framework\TestCase;
 
 /**
  * Tests for some examples.
  */
-class FixturesTest extends \PHPUnit_Framework_TestCase
+class FixturesTest extends TestCase
 {
 
     /**
@@ -28,7 +29,7 @@ class FixturesTest extends \PHPUnit_Framework_TestCase
     /**
      * Set up test.
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->projectRoot = realpath(__DIR__.'/..');
         $this->composerBin = realpath(__DIR__.'/../vendor/bin/composer');
@@ -57,7 +58,7 @@ public function testFixtures($folder, $commands = array(), $files = array())
         // Add this project as local development repository sow we work with
         // the latest code.
         $this->composer('config', 'repositories.dev', 'path', $this->projectRoot);
-        
+
         $output = $this->composer('install');
 
         // Check for deprecation notices.
@@ -67,12 +68,12 @@ public function testFixtures($folder, $commands = array(), $files = array())
         foreach ($commands as $command) {
             call_user_func_array(array($this, 'composer'), $command);
         }
-        
+
         // Check for file existance.
         foreach ($files as $file) {
             $this->assertFileExists($file);
         }
-        
+
         unset($workingDirectory);
     }
 
@@ -94,7 +95,7 @@ public function fixturesProvider()
             ),
         );
     }
-    
+
     /**
      * Run composer command.
      *
@@ -134,7 +135,7 @@ protected function composer($command)
     protected function assertDeprecationNotice($lines)
     {
         foreach ($lines as $line) {
-            $this->assertNotContains('Deprecation Notice:', $line);
+            $this->assertStringNotContainsString('Deprecation Notice:', $line);
         }
     }
 }
diff --git a/tests/PathPreserverTest.php b/tests/PathPreserverTest.php
index 3ad344c..03aff13 100644
--- a/tests/PathPreserverTest.php
+++ b/tests/PathPreserverTest.php
@@ -2,27 +2,35 @@
 
 namespace DrupalComposer\PreservePaths\Tests;
 
-use DrupalComposer\PreservePaths\PathPreserver;
+use Composer\IO\IOInterface;
 use Composer\Util\Filesystem;
-use Composer\Package\Package;
-use Composer\Package\RootPackage;
-use Composer\Composer;
-use Composer\Config;
 use derhasi\tempdirectory\TempDirectory;
+use DrupalComposer\PreservePaths\PathPreserver;
+use PHPUnit\Framework\TestCase;
 
 /**
  * Test for path preserver functionality.
  */
-class PathPreserverTest extends \PHPUnit_Framework_TestCase
+class PathPreserverTest extends TestCase
 {
 
+    /**
+     * @var \Composer\Util\Filesystem
+     */
+    protected $fs;
+
+    /**
+     * @var \Composer\IO\IOInterface
+     */
+    protected $io;
+
     /**
      * set up test environmemt
      */
-    public function setUp()
+    protected function setUp(): void
     {
         $this->fs = new Filesystem();
-        $this->io = $this->getMock('Composer\IO\IOInterface');
+        $this->io = $this->getMockBuilder(IOInterface::class)->getMock();
     }
 
     /**