diff --git a/apps/dav/tests/unit/Connector/Sabre/FileTest.php b/apps/dav/tests/unit/Connector/Sabre/FileTest.php
index 999326463a..31344b3646 100644
--- a/apps/dav/tests/unit/Connector/Sabre/FileTest.php
+++ b/apps/dav/tests/unit/Connector/Sabre/FileTest.php
@@ -48,6 +48,9 @@ class FileTest extends \Test\TestCase {
 
 	public function setUp() {
 		parent::setUp();
+		unset($_SERVER['HTTP_OC_CHUNKED']);
+		unset($_SERVER['CONTENT_LENGTH']);
+		unset($_SERVER['REQUEST_METHOD']);
 
 		\OC_Hook::clear();
 
diff --git a/apps/dav/tests/unit/Connector/Sabre/RequestTest/RequestTest.php b/apps/dav/tests/unit/Connector/Sabre/RequestTest/RequestTest.php
index 8b06678407..10cd73baf6 100644
--- a/apps/dav/tests/unit/Connector/Sabre/RequestTest/RequestTest.php
+++ b/apps/dav/tests/unit/Connector/Sabre/RequestTest/RequestTest.php
@@ -57,6 +57,8 @@ abstract class RequestTest extends TestCase {
 	protected function setUp() {
 		parent::setUp();
 
+		unset($_SERVER['HTTP_OC_CHUNKED']);
+
 		$this->serverFactory = new ServerFactory(
 			\OC::$server->getConfig(),
 			\OC::$server->getLogger(),
diff --git a/apps/files_sharing/tests/Controller/ShareAPIControllerTest.php b/apps/files_sharing/tests/Controller/ShareAPIControllerTest.php
index 97774081b6..726c4bde31 100644
--- a/apps/files_sharing/tests/Controller/ShareAPIControllerTest.php
+++ b/apps/files_sharing/tests/Controller/ShareAPIControllerTest.php
@@ -38,6 +38,7 @@ use OCP\Files\IRootFolder;
 use OCP\Lock\LockedException;
 use OCP\Share\IManager;
 use OCP\Share;
+use Test\TestCase;
 
 /**
  * Class ShareAPIControllerTest
@@ -45,7 +46,7 @@ use OCP\Share;
  * @package OCA\Files_Sharing\Tests\Controller
  * @group DB
  */
-class ShareAPIControllerTest extends \Test\TestCase {
+class ShareAPIControllerTest extends TestCase {
 
 	/** @var string */
 	private $appName = 'files_sharing';
diff --git a/tests/lib/Repair/RepairCollationTest.php b/tests/lib/Repair/RepairCollationTest.php
index 897f772a79..7ff069d37b 100644
--- a/tests/lib/Repair/RepairCollationTest.php
+++ b/tests/lib/Repair/RepairCollationTest.php
@@ -8,10 +8,15 @@
 
 namespace Test\Repair;
 
+use Doctrine\DBAL\Connection;
+use Doctrine\DBAL\Platforms\MySqlPlatform;
+use OC\Repair\Collation;
+use OCP\IDBConnection;
 use OCP\ILogger;
 use OCP\Migration\IOutput;
+use Test\TestCase;
 
-class TestCollationRepair extends \OC\Repair\Collation {
+class TestCollationRepair extends Collation {
 	/**
 	 * @param \Doctrine\DBAL\Connection $connection
 	 * @return string[]
@@ -28,7 +33,7 @@ class TestCollationRepair extends \OC\Repair\Collation {
  *
  * @see \OC\Repair\RepairMimeTypes
  */
-class RepairCollationTest extends \Test\TestCase {
+class RepairCollationTest extends TestCase {
 
 	/**
 	 * @var TestCollationRepair
@@ -36,7 +41,7 @@ class RepairCollationTest extends \Test\TestCase {
 	private $repair;
 
 	/**
-	 * @var \Doctrine\DBAL\Connection
+	 * @var Connection|IDBConnection
 	 */
 	private $connection;
 
@@ -59,7 +64,7 @@ class RepairCollationTest extends \Test\TestCase {
 		$this->connection = \OC::$server->getDatabaseConnection();
 		$this->logger = $this->createMock(ILogger::class);
 		$this->config = \OC::$server->getConfig();
-		if (!$this->connection->getDatabasePlatform() instanceof \Doctrine\DBAL\Platforms\MySqlPlatform) {
+		if (!$this->connection->getDatabasePlatform() instanceof MySqlPlatform) {
 			$this->markTestSkipped("Test only relevant on MySql");
 		}
 
diff --git a/tests/phpunit-autotest.xml b/tests/phpunit-autotest.xml
index ba16bbdbaa..9a9c9c957e 100644
--- a/tests/phpunit-autotest.xml
+++ b/tests/phpunit-autotest.xml
@@ -2,6 +2,7 @@
 <phpunit bootstrap="bootstrap.php"
 		 strict="true"
 		 verbose="true"
+		 backupGlobals="false"
 		 timeoutForSmallTests="900"
 		 timeoutForMediumTests="900"
 		 timeoutForLargeTests="900"