diff --git a/composer.json b/composer.json
index c82b8e87..66936d35 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
         "composer-plugin-api": "^1.0"
     },
     "require-dev": {
-        "phpunit/phpunit":   "^5.2.8",
+        "phpunit/phpunit":   "^5.4",
         "composer/composer": "^1.0.0-ALPHA11@ALPHA"
     },
     "autoload": {
diff --git a/test/PackageVersionsTest/InstallerTest.php b/test/PackageVersionsTest/InstallerTest.php
index 78d47a2f..d53e5916 100644
--- a/test/PackageVersionsTest/InstallerTest.php
+++ b/test/PackageVersionsTest/InstallerTest.php
@@ -44,7 +44,7 @@ final class InstallerTest extends PHPUnit_Framework_TestCase
 
     /**
      * {@inheritDoc}
-     * 
+     *
      * @throws \PHPUnit_Framework_Exception
      */
     protected function setUp()
@@ -52,8 +52,8 @@ protected function setUp()
         parent::setUp();
 
         $this->installer       = new Installer();
-        $this->io              = $this->getMock(IOInterface::class);
-        $this->composer        = $this->getMock(Composer::class);
+        $this->io              = $this->createMock(IOInterface::class);
+        $this->composer        = $this->createMock(Composer::class);
         $this->eventDispatcher = $this->getMockBuilder(EventDispatcher::class)->disableOriginalConstructor()->getMock();
 
         $this->composer->expects(self::any())->method('getEventDispatcher')->willReturn($this->eventDispatcher);
@@ -89,8 +89,8 @@ public function testDumpVersionsClass()
         $locker            = $this->getMockBuilder(Locker::class)->disableOriginalConstructor()->getMock();
         $repositoryManager = $this->getMockBuilder(RepositoryManager::class)->disableOriginalConstructor()->getMock();
         $installManager    = $this->getMockBuilder(InstallationManager::class)->disableOriginalConstructor()->getMock();
-        $repository        = $this->getMock(InstalledRepositoryInterface::class);
-        $package           = $this->getMock(RootPackageInterface::class);
+        $repository        = $this->createMock(InstalledRepositoryInterface::class);
+        $package           = $this->createMock(RootPackageInterface::class);
 
         $vendorDir = sys_get_temp_dir() . '/' . uniqid('InstallerTest', true);
 
@@ -201,8 +201,8 @@ public function testDumpVersionsClassNoDev()
         $locker            = $this->getMockBuilder(Locker::class)->disableOriginalConstructor()->getMock();
         $repositoryManager = $this->getMockBuilder(RepositoryManager::class)->disableOriginalConstructor()->getMock();
         $installManager    = $this->getMockBuilder(InstallationManager::class)->disableOriginalConstructor()->getMock();
-        $repository        = $this->getMock(InstalledRepositoryInterface::class);
-        $package           = $this->getMock(RootPackageInterface::class);
+        $repository        = $this->createMock(InstalledRepositoryInterface::class);
+        $package           = $this->createMock(RootPackageInterface::class);
 
         $vendorDir = sys_get_temp_dir() . '/' . uniqid('InstallerTest', true);
 
@@ -299,7 +299,7 @@ public static function getVersion(string $packageName) : string
 
     /**
      * @group #12
-     * 
+     *
      * @throws \RuntimeException
      */
     public function testDumpVersionsWithoutPackageSourceDetails()
@@ -308,8 +308,8 @@ public function testDumpVersionsWithoutPackageSourceDetails()
         $locker            = $this->getMockBuilder(Locker::class)->disableOriginalConstructor()->getMock();
         $repositoryManager = $this->getMockBuilder(RepositoryManager::class)->disableOriginalConstructor()->getMock();
         $installManager    = $this->getMockBuilder(InstallationManager::class)->disableOriginalConstructor()->getMock();
-        $repository        = $this->getMock(InstalledRepositoryInterface::class);
-        $package           = $this->getMock(RootPackageInterface::class);
+        $repository        = $this->createMock(InstalledRepositoryInterface::class);
+        $package           = $this->createMock(RootPackageInterface::class);
 
         $vendorDir = sys_get_temp_dir() . '/' . uniqid('InstallerTest', true);
 
@@ -415,7 +415,7 @@ public function testDumpsVersionsClassToSpecificLocation(RootPackageInterface $r
         $locker            = $this->getMockBuilder(Locker::class)->disableOriginalConstructor()->getMock();
         $repositoryManager = $this->getMockBuilder(RepositoryManager::class)->disableOriginalConstructor()->getMock();
         $installManager    = $this->getMockBuilder(InstallationManager::class)->disableOriginalConstructor()->getMock();
-        $repository        = $this->getMock(InstalledRepositoryInterface::class);
+        $repository        = $this->createMock(InstalledRepositoryInterface::class);
 
         $vendorDir = sys_get_temp_dir() . '/' . uniqid('InstallerTest', true) . '/vendor';