diff --git a/src/Arr.php b/src/Arr.php
index 8a3abea..cde3f29 100644
--- a/src/Arr.php
+++ b/src/Arr.php
@@ -38,7 +38,7 @@ public static function unique(array $array, bool $keepKeys = false): array
 
                 $uniqueArray[$value] = $key;
             }
-            
+
             return \array_flip($uniqueArray);
         }
 
diff --git a/src/FS.php b/src/FS.php
index 2313dff..a7f8a8d 100644
--- a/src/FS.php
+++ b/src/FS.php
@@ -173,9 +173,14 @@ public static function openFile(string $filepath): ?string
 
         $realPath = \realpath($filepath);
         if ($realPath !== false) {
-            $handle = \fopen($realPath, 'r');
+            $handle   = \fopen($realPath, 'r');
+            $fileSize = (int)\filesize($realPath);
+            if ($fileSize === 0) {
+                return null;
+            }
+
             if ($handle !== false) {
-                $contents = (string)\fread($handle, (int)\filesize($realPath));
+                $contents = (string)\fread($handle, $fileSize);
                 \fclose($handle);
             }
         }
@@ -370,9 +375,9 @@ public static function clean(?string $path, string $dirSep = \DIRECTORY_SEPARATO
         $path = \trim((string)$path);
 
         if (($dirSep === '\\') && ($path[0] === '\\') && ($path[1] === '\\')) {
-            $path = '\\' . \preg_replace('#[/\\\\]+#', $dirSep, $path);
+            $path = '\\' . \preg_replace('#[/\\\]+#', $dirSep, $path);
         } else {
-            $path = (string)\preg_replace('#[/\\\\]+#', $dirSep, $path);
+            $path = (string)\preg_replace('#[/\\\]+#', $dirSep, $path);
         }
 
         return $path;
diff --git a/tests/FileSystemTest.php b/tests/FileSystemTest.php
index 80d7809..634507d 100644
--- a/tests/FileSystemTest.php
+++ b/tests/FileSystemTest.php
@@ -394,9 +394,9 @@ public function testClean(): void
         isSame('/path/path', FS::clean('///path///path'));
         isSame('/path/path/path', FS::clean('///path///path/path'));
         isSame('/path/path/path/', FS::clean('\path\path\path\\\\\\\\'));
-        isSame('\\path\\path\\path\\', FS::clean('\path\path\path\\\\\\\\', '\\'));
-        isSame('\\path\\path\\path\\', FS::clean('\\path\\path\\path\\\\\\\\', '\\'));
-        isSame('\\\\path\\path\\path\\', FS::clean('\\\\path\\path\\path\\\\\\\\', '\\'));
+        isSame('\path\path\path\\', FS::clean('\path\path\path\\\\\\\\', '\\'));
+        isSame('\path\path\path\\', FS::clean('\path\path\path\\\\\\\\', '\\'));
+        isSame('\\\path\path\path\\', FS::clean('\\\path\path\path\\\\\\\\', '\\'));
 
         isSame('../../path/', FS::clean('..///..///path/', '/'));
         isSame('./../path/', FS::clean('.///..///path/', '/'));
@@ -438,10 +438,10 @@ public function testGetRelative(): void
 
         $root = __DIR__ . '/..';
         isSame('tests/FileSystemTest.php', FS::getRelative($file, $root, '/'));
-        isSame('tests\\FileSystemTest.php', FS::getRelative($file, $root, '\\'));
+        isSame('tests\FileSystemTest.php', FS::getRelative($file, $root, '\\'));
 
         $root = null;
         isSame('tests/FileSystemTest.php', FS::getRelative($file, $root, '/'));
-        isSame('tests\\FileSystemTest.php', FS::getRelative($file, $root, '\\'));
+        isSame('tests\FileSystemTest.php', FS::getRelative($file, $root, '\\'));
     }
 }
diff --git a/tests/StringTest.php b/tests/StringTest.php
index abbe8bb..69f2657 100644
--- a/tests/StringTest.php
+++ b/tests/StringTest.php
@@ -74,7 +74,7 @@ public function testClean(): void
         $input = ' <b>ASDF</b> !@#$%^&*()_+"\';:>< ';
 
         isSame('ASDF !@#$%^&*()_+"\';:><', Str::clean($input));
-        isSame('asdf !@#$%^&*()_+\\"\\\';:><', Str::clean($input, true, true));
+        isSame('asdf !@#$%^&*()_+\"\\\';:><', Str::clean($input, true, true));
     }
 
     public function testParseLines(): void
@@ -272,7 +272,7 @@ public function testEsc(): void
     {
         isSame(
             '&lt;a href="/test"&gt;Test !@#$%^&amp;*()_+\/&lt;/a&gt;',
-            Str::esc('<a href="/test">Test !@#$%^&*()_+\\/</a>'),
+            Str::esc('<a href="/test">Test !@#$%^&*()_+\/</a>'),
         );
     }
 
@@ -280,7 +280,7 @@ public function testEscXML(): void
     {
         isSame(
             '&lt;a href=&quot;/test&quot;&gt;Test!@#$%^&amp;*()_+\/&lt;/a&gt;',
-            Str::escXml('<a href="/test">Test!@#$%^&*()_+\\/</a>'),
+            Str::escXml('<a href="/test">Test!@#$%^&*()_+\/</a>'),
         );
     }
 
@@ -333,10 +333,10 @@ public function testTestName2Human(): void
         isSame('Function IE Test', Str::testName2Human('Test_FunctionIE_TestTest'));
         isSame('Test Function IE Test', Str::testName2Human('Test_testFunctionIE_TestTest'));
 
-        isSame('Function IE', Str::testName2Human('\\JBZoo\\Test_FunctionIE_Test'));
-        isSame('Function IE', Str::testName2Human('\\JBZoo\\PHPHunit\\Test_FunctionIE_Test'));
-        isSame('Function IE', Str::testName2Human('\\JBZoo\\PHPHunit\\Some\\Test_FunctionIE_Test'));
-        isSame('Function IE', Str::testName2Human('\\JBZoo\\PHPHunit\\Some\\Some\\Test_FunctionIE_Test'));
+        isSame('Function IE', Str::testName2Human('\JBZoo\Test_FunctionIE_Test'));
+        isSame('Function IE', Str::testName2Human('\JBZoo\PHPHunit\Test_FunctionIE_Test'));
+        isSame('Function IE', Str::testName2Human('\JBZoo\PHPHunit\Some\Test_FunctionIE_Test'));
+        isSame('Function IE', Str::testName2Human('\JBZoo\PHPHunit\Some\Some\Test_FunctionIE_Test'));
     }
 
     public function testGenerateUUID(): void
diff --git a/tests/SysTest.php b/tests/SysTest.php
index dbabf17..fe3a2cc 100644
--- a/tests/SysTest.php
+++ b/tests/SysTest.php
@@ -89,7 +89,7 @@ public function testGetDocumentRoot(): void
         $_SERVER['DOCUMENT_ROOT'] = '../../';
         isSame(\realpath('../../'), Sys::getDocRoot());
 
-        $_SERVER['DOCUMENT_ROOT'] = __DIR__ . '\\..\\';
+        $_SERVER['DOCUMENT_ROOT'] = __DIR__ . '\..\\';
         isSame(PROJECT_ROOT, Sys::getDocRoot());
     }
 
diff --git a/tests/XmlTest.php b/tests/XmlTest.php
index 7ad8832..0dedf15 100644
--- a/tests/XmlTest.php
+++ b/tests/XmlTest.php
@@ -263,7 +263,7 @@ public function testEscape(): void
     {
         isSame(
             '&lt;a href=&quot;/test&quot;&gt;Test!@#$%^&amp;*()_+\/&lt;/a&gt;',
-            Xml::escape('<a href="/test">Test!@#$%^&*()_+\\/</a>'),
+            Xml::escape('<a href="/test">Test!@#$%^&*()_+\/</a>'),
         );
     }