diff --git a/.travis.yml b/.travis.yml
index b848430..af96326 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,7 @@ php:
   - 7.1
   - 7.2
   - 7.3
+  - 7.4
 
 before_script:
   - composer selfupdate
diff --git a/composer.json b/composer.json
index 290ee84..057ec23 100644
--- a/composer.json
+++ b/composer.json
@@ -3,8 +3,8 @@
   "description": "File uploading library capable of handling large/chunked/multiple file uploads",
   "license": "MIT",
   "autoload": {
-    "psr-0": {
-      "FileUpload\\": "src/"
+    "psr-4": {
+      "FileUpload\\": "src/FileUpload"
     }
   },
   "require": {
diff --git a/src/FileUpload/FileNameGenerator/Simple.php b/src/FileUpload/FileNameGenerator/Simple.php
index 0b0fdcc..2722d7b 100644
--- a/src/FileUpload/FileNameGenerator/Simple.php
+++ b/src/FileUpload/FileNameGenerator/Simple.php
@@ -56,11 +56,15 @@ public function getFileName($source_name, $type, $tmp_name, $index, $content_ran
      */
     protected function getUniqueFilename($name, $type, $index, $content_range)
     {
+        if (! is_array($content_range)) {
+            $content_range = [0];
+        }
+
         while ($this->filesystem->isDir($this->pathresolver->getUploadPath($name))) {
             $name = $this->pathresolver->upcountName($name);
         }
 
-        $uploaded_bytes = Util::fixIntegerOverflow(intval($content_range[1]));
+        $uploaded_bytes = Util::fixIntegerOverflow(intval($content_range[1] ?? $content_range[0]));
 
         while ($this->filesystem->isFile($this->pathresolver->getUploadPath($name))) {
             if ($uploaded_bytes == $this->filesystem->getFilesize($this->pathresolver->getUploadPath($name))) {
diff --git a/src/FileUpload/FileNameGenerator/Slug.php b/src/FileUpload/FileNameGenerator/Slug.php
index dbeafb4..8f88b0c 100644
--- a/src/FileUpload/FileNameGenerator/Slug.php
+++ b/src/FileUpload/FileNameGenerator/Slug.php
@@ -59,11 +59,15 @@ public function getFileName($source_name, $type, $tmp_name, $index, $content_ran
      */
     protected function getUniqueFilename($name, $type, $index, $content_range)
     {
+        if (! is_array($content_range)) {
+            $content_range = [0];
+        }
+
         while ($this->filesystem->isDir($this->pathresolver->getUploadPath($this->getSluggedFileName($name)))) {
             $name = $this->pathresolver->upcountName($name);
         }
 
-        $uploaded_bytes = Util::fixIntegerOverflow(intval($content_range[1]));
+        $uploaded_bytes = Util::fixIntegerOverflow(intval($content_range[1] ?? $content_range[0]));
 
         while ($this->filesystem->isFile($this->pathresolver->getUploadPath($this->getSluggedFileName($name)))) {
             if ($uploaded_bytes == $this->filesystem->getFilesize($this->pathresolver->getUploadPath($this->getSluggedFileName($name)))) {
@@ -107,7 +111,7 @@ private function slugify($text)
         $text = strtolower($text);
         // remove unwanted characters
         $text = preg_replace('~[^-\w]+~', '', $text);
-        
+
         if (empty($text)) {
             return 'n-a';
         }
diff --git a/tests/FileUpload/FileNameGenerator/MD5Test.php b/tests/FileUpload/FileNameGenerator/MD5Test.php
index df57055..6b87f43 100644
--- a/tests/FileUpload/FileNameGenerator/MD5Test.php
+++ b/tests/FileUpload/FileNameGenerator/MD5Test.php
@@ -11,7 +11,7 @@ class MD5Test extends TestCase
 {
     protected $filesystem;
 
-    public function setUp()
+    protected function setUp()
     {
         $playground_path = __DIR__ . '/../../playground';
         $fixtures_path = __DIR__ . '/../../fixtures';
diff --git a/tests/FileUpload/FileSystem/SimpleTest.php b/tests/FileUpload/FileSystem/SimpleTest.php
index fb80d6f..80d690f 100644
--- a/tests/FileUpload/FileSystem/SimpleTest.php
+++ b/tests/FileUpload/FileSystem/SimpleTest.php
@@ -8,7 +8,7 @@ class SimpleTest extends TestCase
 {
     protected $filesystem;
 
-    public function setUp()
+    protected function setUp()
     {
         $playground_path = __DIR__ . '/../../playground';
         $fixtures_path = __DIR__ . '/../../fixtures';
@@ -42,7 +42,7 @@ public function testWriteToFile()
         $path = __DIR__ . '/../../playground/test.1.txt';
 
         $this->filesystem->writeToFile($path, $this->filesystem->getFileStream($yadda));
-        $this->assertEquals(file_get_contents($yadda), file_get_contents($path));
+        $this->assertFileEquals($yadda, $path);
 
         $this->filesystem->unlink($path);
     }
diff --git a/tests/FileUpload/FileUploadTest.php b/tests/FileUpload/FileUploadTest.php
index 6cfdd74..c6c3857 100644
--- a/tests/FileUpload/FileUploadTest.php
+++ b/tests/FileUpload/FileUploadTest.php
@@ -6,7 +6,7 @@
 
 class FileUploadTest extends TestCase
 {
-    public function setUp()
+    protected function setUp()
     {
         $playground_path = __DIR__ . '/../playground';
         $fixtures_path = __DIR__ . '/../fixtures';
diff --git a/tests/FileUpload/Validator/DimensionValidatorTest.php b/tests/FileUpload/Validator/DimensionValidatorTest.php
index 84d21e3..2f2af59 100644
--- a/tests/FileUpload/Validator/DimensionValidatorTest.php
+++ b/tests/FileUpload/Validator/DimensionValidatorTest.php
@@ -297,7 +297,7 @@ public function testSetErrorMessages()
         );
     }
 
-    public function setUp()
+    protected function setUp()
     {
         $this->directory = __DIR__ . '/../../fixtures/';
     }
diff --git a/tests/FileUpload/Validator/MimeTypeValidatorTest.php b/tests/FileUpload/Validator/MimeTypeValidatorTest.php
index f4f7f78..2ba6046 100644
--- a/tests/FileUpload/Validator/MimeTypeValidatorTest.php
+++ b/tests/FileUpload/Validator/MimeTypeValidatorTest.php
@@ -42,7 +42,7 @@ public function testInvalidMimeType()
         $this->assertFalse($this->validator->validate($file, $_FILES['file']['size']));
     }
 
-    public function setUp()
+    protected function setUp()
     {
         $this->directory = __DIR__ . '/../../fixtures/';
 
diff --git a/tests/FileUpload/Validator/SimpleTest.php b/tests/FileUpload/Validator/SimpleTest.php
index ede97f2..d898509 100644
--- a/tests/FileUpload/Validator/SimpleTest.php
+++ b/tests/FileUpload/Validator/SimpleTest.php
@@ -70,7 +70,7 @@ public function testSetErrorMessages()
         $this->assertEquals($errorMessage, $file->error);
     }
 
-    public function setUp()
+    protected function setUp()
     {
         $this->directory = __DIR__ . '/../../fixtures/';
 
diff --git a/tests/FileUpload/Validator/SizeValidatorTest.php b/tests/FileUpload/Validator/SizeValidatorTest.php
index abf265e..1bf4a1f 100644
--- a/tests/FileUpload/Validator/SizeValidatorTest.php
+++ b/tests/FileUpload/Validator/SizeValidatorTest.php
@@ -11,7 +11,7 @@ class SizeValidatorTest extends TestCase
     protected $validator;
     protected $file;
 
-    public function setUp()
+    protected function setUp()
     {
         $this->directory = __DIR__ . '/../../fixtures/';