diff --git a/Factory/PsrHttpFactory.php b/Factory/PsrHttpFactory.php
index fcb80d6..d19baa1 100644
--- a/Factory/PsrHttpFactory.php
+++ b/Factory/PsrHttpFactory.php
@@ -89,7 +89,7 @@ private function getFiles(array $uploadedFiles)
 
         foreach ($uploadedFiles as $key => $value) {
             if (null === $value) {
-                $files[$key] = $this->uploadedFileFactory->createUploadedFile($this->streamFactory->createStream(), 0, UPLOAD_ERR_NO_FILE);
+                $files[$key] = $this->uploadedFileFactory->createUploadedFile($this->streamFactory->createStream(), 0, \UPLOAD_ERR_NO_FILE);
                 continue;
             }
             if ($value instanceof UploadedFile) {
diff --git a/Factory/UploadedFile.php b/Factory/UploadedFile.php
index 804f747..53aa37a 100644
--- a/Factory/UploadedFile.php
+++ b/Factory/UploadedFile.php
@@ -29,7 +29,7 @@ public function __construct(UploadedFileInterface $psrUploadedFile, callable $ge
         $error = $psrUploadedFile->getError();
         $path = '';
 
-        if (UPLOAD_ERR_NO_FILE !== $error) {
+        if (\UPLOAD_ERR_NO_FILE !== $error) {
             $path = $psrUploadedFile->getStream()->getMetadata('uri') ?? '';
 
             if ($this->test = !\is_string($path) || !is_uploaded_file($path)) {
diff --git a/Tests/Factory/AbstractHttpMessageFactoryTest.php b/Tests/Factory/AbstractHttpMessageFactoryTest.php
index 2176ae8..82d3fc7 100644
--- a/Tests/Factory/AbstractHttpMessageFactoryTest.php
+++ b/Tests/Factory/AbstractHttpMessageFactoryTest.php
@@ -31,7 +31,7 @@ abstract class AbstractHttpMessageFactoryTest extends TestCase
 
     abstract protected function buildHttpMessageFactory(): HttpMessageFactoryInterface;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         $this->factory = $this->buildHttpMessageFactory();
         $this->tmpDir = sys_get_temp_dir();
@@ -61,8 +61,8 @@ public function testCreateRequest()
                 'c2' => ['c3' => 'bar'],
             ],
             [
-                'f1' => $this->createUploadedFile('F1', 'f1.txt', 'text/plain', UPLOAD_ERR_OK),
-                'foo' => ['f2' => $this->createUploadedFile('F2', 'f2.txt', 'text/plain', UPLOAD_ERR_OK)],
+                'f1' => $this->createUploadedFile('F1', 'f1.txt', 'text/plain', \UPLOAD_ERR_OK),
+                'foo' => ['f2' => $this->createUploadedFile('F2', 'f2.txt', 'text/plain', \UPLOAD_ERR_OK)],
             ],
             [
                 'REQUEST_METHOD' => 'POST',
@@ -102,12 +102,12 @@ public function testCreateRequest()
         $this->assertEquals('F1', $uploadedFiles['f1']->getStream()->__toString());
         $this->assertEquals('f1.txt', $uploadedFiles['f1']->getClientFilename());
         $this->assertEquals('text/plain', $uploadedFiles['f1']->getClientMediaType());
-        $this->assertEquals(UPLOAD_ERR_OK, $uploadedFiles['f1']->getError());
+        $this->assertEquals(\UPLOAD_ERR_OK, $uploadedFiles['f1']->getError());
 
         $this->assertEquals('F2', $uploadedFiles['foo']['f2']->getStream()->__toString());
         $this->assertEquals('f2.txt', $uploadedFiles['foo']['f2']->getClientFilename());
         $this->assertEquals('text/plain', $uploadedFiles['foo']['f2']->getClientMediaType());
-        $this->assertEquals(UPLOAD_ERR_OK, $uploadedFiles['foo']['f2']->getError());
+        $this->assertEquals(\UPLOAD_ERR_OK, $uploadedFiles['foo']['f2']->getError());
 
         $serverParams = $psrRequest->getServerParams();
         $this->assertEquals('POST', $serverParams['REQUEST_METHOD']);
@@ -201,10 +201,10 @@ public function testCreateResponseFromBinaryFileWithRange()
 
     public function testUploadErrNoFile()
     {
-        $file = new UploadedFile('', '', null, UPLOAD_ERR_NO_FILE, true);
+        $file = new UploadedFile('', '', null, \UPLOAD_ERR_NO_FILE, true);
 
         $this->assertEquals(0, $file->getSize());
-        $this->assertEquals(UPLOAD_ERR_NO_FILE, $file->getError());
+        $this->assertEquals(\UPLOAD_ERR_NO_FILE, $file->getError());
         $this->assertFalse($file->getSize(), 'SplFile::getSize() returns false on error');
 
         $request = new Request(
@@ -214,7 +214,7 @@ public function testUploadErrNoFile()
             [],
             [
             'f1' => $file,
-            'f2' => ['name' => null, 'type' => null, 'tmp_name' => null, 'error' => UPLOAD_ERR_NO_FILE, 'size' => 0],
+            'f2' => ['name' => null, 'type' => null, 'tmp_name' => null, 'error' => \UPLOAD_ERR_NO_FILE, 'size' => 0],
           ],
             [
             'REQUEST_METHOD' => 'POST',
@@ -228,7 +228,7 @@ public function testUploadErrNoFile()
 
         $uploadedFiles = $psrRequest->getUploadedFiles();
 
-        $this->assertEquals(UPLOAD_ERR_NO_FILE, $uploadedFiles['f1']->getError());
-        $this->assertEquals(UPLOAD_ERR_NO_FILE, $uploadedFiles['f2']->getError());
+        $this->assertEquals(\UPLOAD_ERR_NO_FILE, $uploadedFiles['f1']->getError());
+        $this->assertEquals(\UPLOAD_ERR_NO_FILE, $uploadedFiles['f2']->getError());
     }
 }
diff --git a/Tests/Factory/HttpFoundationFactoryTest.php b/Tests/Factory/HttpFoundationFactoryTest.php
index e35a789..3a00e2f 100644
--- a/Tests/Factory/HttpFoundationFactoryTest.php
+++ b/Tests/Factory/HttpFoundationFactoryTest.php
@@ -34,7 +34,7 @@ class HttpFoundationFactoryTest extends TestCase
     /** @var string */
     private $tmpDir;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
         $this->factory = new HttpFoundationFactory();
         $this->tmpDir = sys_get_temp_dir();
@@ -57,11 +57,11 @@ public function testCreateRequest()
             ['city' => 'Lille'],
             ['url' => 'http://les-tilleuls.coop'],
             [
-                'doc1' => $this->createUploadedFile('Doc 1', UPLOAD_ERR_OK, 'doc1.txt', 'text/plain'),
+                'doc1' => $this->createUploadedFile('Doc 1', \UPLOAD_ERR_OK, 'doc1.txt', 'text/plain'),
                 'nested' => [
                     'docs' => [
-                        $this->createUploadedFile('Doc 2', UPLOAD_ERR_OK, 'doc2.txt', 'text/plain'),
-                        $this->createUploadedFile('Doc 3', UPLOAD_ERR_OK, 'doc3.txt', 'text/plain'),
+                        $this->createUploadedFile('Doc 2', \UPLOAD_ERR_OK, 'doc2.txt', 'text/plain'),
+                        $this->createUploadedFile('Doc 3', \UPLOAD_ERR_OK, 'doc3.txt', 'text/plain'),
                     ],
                 ],
             ],
@@ -168,7 +168,7 @@ public function testCreateRequestWithUri()
 
     public function testCreateUploadedFile()
     {
-        $uploadedFile = $this->createUploadedFile('An uploaded file.', UPLOAD_ERR_OK, 'myfile.txt', 'text/plain');
+        $uploadedFile = $this->createUploadedFile('An uploaded file.', \UPLOAD_ERR_OK, 'myfile.txt', 'text/plain');
         $symfonyUploadedFile = $this->callCreateUploadedFile($uploadedFile);
         $size = $symfonyUploadedFile->getSize();
 
@@ -176,7 +176,7 @@ public function testCreateUploadedFile()
         $symfonyUploadedFile->move($this->tmpDir, $uniqid);
 
         $this->assertEquals($uploadedFile->getSize(), $size);
-        $this->assertEquals(UPLOAD_ERR_OK, $symfonyUploadedFile->getError());
+        $this->assertEquals(\UPLOAD_ERR_OK, $symfonyUploadedFile->getError());
         $this->assertEquals('myfile.txt', $symfonyUploadedFile->getClientOriginalName());
         $this->assertEquals('txt', $symfonyUploadedFile->getClientOriginalExtension());
         $this->assertEquals('text/plain', $symfonyUploadedFile->getClientMimeType());
@@ -188,10 +188,10 @@ public function testCreateUploadedFileWithError()
         $this->expectException(FileException::class);
         $this->expectExceptionMessage('The file "e" could not be written on disk.');
 
-        $uploadedFile = $this->createUploadedFile('Error.', UPLOAD_ERR_CANT_WRITE, 'e', 'text/plain');
+        $uploadedFile = $this->createUploadedFile('Error.', \UPLOAD_ERR_CANT_WRITE, 'e', 'text/plain');
         $symfonyUploadedFile = $this->callCreateUploadedFile($uploadedFile);
 
-        $this->assertEquals(UPLOAD_ERR_CANT_WRITE, $symfonyUploadedFile->getError());
+        $this->assertEquals(\UPLOAD_ERR_CANT_WRITE, $symfonyUploadedFile->getError());
 
         $symfonyUploadedFile->move($this->tmpDir, 'shouldFail.txt');
     }
diff --git a/Tests/Fixtures/Stream.php b/Tests/Fixtures/Stream.php
index 06fff28..2cb4ab2 100644
--- a/Tests/Fixtures/Stream.php
+++ b/Tests/Fixtures/Stream.php
@@ -59,7 +59,7 @@ public function isSeekable()
         return true;
     }
 
-    public function seek($offset, $whence = SEEK_SET)
+    public function seek($offset, $whence = \SEEK_SET)
     {
     }
 
diff --git a/Tests/Fixtures/UploadedFile.php b/Tests/Fixtures/UploadedFile.php
index f58a4bd..93b3214 100644
--- a/Tests/Fixtures/UploadedFile.php
+++ b/Tests/Fixtures/UploadedFile.php
@@ -24,7 +24,7 @@ class UploadedFile implements UploadedFileInterface
     private $clientFileName;
     private $clientMediaType;
 
-    public function __construct($filePath, $size = null, $error = UPLOAD_ERR_OK, $clientFileName = null, $clientMediaType = null)
+    public function __construct($filePath, $size = null, $error = \UPLOAD_ERR_OK, $clientFileName = null, $clientMediaType = null)
     {
         $this->filePath = $filePath;
         $this->size = $size;
diff --git a/Tests/Functional/CovertTest.php b/Tests/Functional/CovertTest.php
index 4fc6890..f460b0e 100644
--- a/Tests/Functional/CovertTest.php
+++ b/Tests/Functional/CovertTest.php
@@ -36,9 +36,9 @@ class CovertTest extends TestCase
 {
     private $tmpDir;
 
-    public function setUp(): void
+    protected function setUp(): void
     {
-        if (!class_exists('Nyholm\Psr7\ServerRequest')) {
+        if (!class_exists(Psr7Request::class)) {
             $this->markTestSkipped('nyholm/psr7 is not installed.');
         }
 
@@ -124,8 +124,8 @@ public function requestProvider()
                 'c2' => ['c3' => 'bar'],
             ],
             [
-                'f1' => $this->createUploadedFile('F1', 'f1.txt', 'text/plain', UPLOAD_ERR_OK),
-                'foo' => ['f2' => $this->createUploadedFile('F2', 'f2.txt', 'text/plain', UPLOAD_ERR_OK)],
+                'f1' => $this->createUploadedFile('F1', 'f1.txt', 'text/plain', \UPLOAD_ERR_OK),
+                'foo' => ['f2' => $this->createUploadedFile('F2', 'f2.txt', 'text/plain', \UPLOAD_ERR_OK)],
             ],
             [
                 'REQUEST_METHOD' => 'POST',