diff --git a/src/Config.php b/src/Config.php
index c0494dbabc..ac3cff705f 100644
--- a/src/Config.php
+++ b/src/Config.php
@@ -450,7 +450,7 @@ public function __construct(array $cliArgs=[], $dieOnUnknownArg=true)
         }//end if
 
         if (defined('STDIN') === false
-            || stripos(PHP_OS, 'WIN') === 0
+            || PHP_OS_FAMILY === 'Windows'
         ) {
             return;
         }
@@ -1614,7 +1614,7 @@ public static function getExecutablePath($name)
             return self::$executablePaths[$name];
         }
 
-        if (stripos(PHP_OS, 'WIN') === 0) {
+        if (PHP_OS_FAMILY === 'Windows') {
             $cmd = 'where '.escapeshellarg($name).' 2> nul';
         } else {
             $cmd = 'which '.escapeshellarg($name).' 2> /dev/null';
diff --git a/src/Fixer.php b/src/Fixer.php
index 709d193aa1..cbdf687f49 100644
--- a/src/Fixer.php
+++ b/src/Fixer.php
@@ -284,7 +284,7 @@ public function generateDiff($filePath=null, $colors=true)
         ];
 
         $options = null;
-        if (stripos(PHP_OS, 'WIN') === 0) {
+        if (PHP_OS_FAMILY === 'Windows') {
             $options = ['bypass_shell' => true];
         }
 
diff --git a/src/Reports/Code.php b/src/Reports/Code.php
index 1a39f06f92..2299b018b1 100644
--- a/src/Reports/Code.php
+++ b/src/Reports/Code.php
@@ -230,7 +230,7 @@ public function generateFileReport($report, File $phpcsFile, $showSources=false,
                     if (strpos($tokenContent, "\t") !== false) {
                         $token            = $tokens[$i];
                         $token['content'] = $tokenContent;
-                        if (stripos(PHP_OS, 'WIN') === 0) {
+                        if (PHP_OS_FAMILY === 'Windows') {
                             $tab = "\000";
                         } else {
                             $tab = "\033[30;1m»\033[0m";
diff --git a/src/Standards/Generic/Tests/Files/ExecutableFileUnitTest.php b/src/Standards/Generic/Tests/Files/ExecutableFileUnitTest.php
index 55d5ba1baa..1b15736b83 100644
--- a/src/Standards/Generic/Tests/Files/ExecutableFileUnitTest.php
+++ b/src/Standards/Generic/Tests/Files/ExecutableFileUnitTest.php
@@ -28,7 +28,7 @@ final class ExecutableFileUnitTest extends AbstractSniffTestCase
     protected function shouldSkipTest()
     {
         // Skip on Windows which doesn't have the concept of executable files.
-        return (stripos(PHP_OS, 'WIN') === 0);
+        return PHP_OS_FAMILY === 'Windows';
 
     }//end shouldSkipTest()
 
diff --git a/src/Tokenizers/PHP.php b/src/Tokenizers/PHP.php
index 31015cac97..f4360d9e7a 100644
--- a/src/Tokenizers/PHP.php
+++ b/src/Tokenizers/PHP.php
@@ -528,7 +528,7 @@ protected function tokenize($string)
         if (PHP_CODESNIFFER_VERBOSITY > 1) {
             StatusWriter::write('*** START PHP TOKENIZING ***', 1);
             $isWin = false;
-            if (stripos(PHP_OS, 'WIN') === 0) {
+            if (PHP_OS_FAMILY === 'Windows') {
                 $isWin = true;
             }
         }
diff --git a/src/Util/Common.php b/src/Util/Common.php
index 5ca34ded59..5216a24fad 100644
--- a/src/Util/Common.php
+++ b/src/Util/Common.php
@@ -253,7 +253,7 @@ public static function escapeshellcmd($cmd)
     {
         $cmd = escapeshellcmd($cmd);
 
-        if (stripos(PHP_OS, 'WIN') === 0) {
+        if (PHP_OS_FAMILY === 'Windows') {
             // Spaces are not escaped by escapeshellcmd on Windows, but need to be
             // for the command to be able to execute.
             $cmd = preg_replace('`(?<!^) `', '^ ', $cmd);
@@ -278,7 +278,7 @@ public static function escapeshellcmd($cmd)
      */
     public static function prepareForOutput($content, $exclude=[])
     {
-        if (stripos(PHP_OS, 'WIN') === 0) {
+        if (PHP_OS_FAMILY === 'Windows') {
             if (in_array("\r", $exclude, true) === false) {
                 $content = str_replace("\r", '\r', $content);
             }
diff --git a/tests/Core/Ruleset/ExpandRulesetReferenceTest.php b/tests/Core/Ruleset/ExpandRulesetReferenceTest.php
index 284bdf7fb8..505c54d164 100644
--- a/tests/Core/Ruleset/ExpandRulesetReferenceTest.php
+++ b/tests/Core/Ruleset/ExpandRulesetReferenceTest.php
@@ -115,7 +115,7 @@ public static function dataUnresolvableReferenceThrowsException()
         ];
 
         // Add tests which are only relevant for case-sensitive OSes.
-        if (stripos(PHP_OS, 'WIN') === false) {
+        if (PHP_OS_FAMILY !== 'Windows') {
             $data['Referencing an existing sniff, but there is a case mismatch (OS-dependent) [1]'] = [
                 'standard'    => 'ExpandRulesetReferenceCaseMismatch1Test.xml',
                 'replacement' => 'psr12.functions.nullabletypedeclaration',
diff --git a/tests/Core/Util/Common/EscapeshellcmdTest.php b/tests/Core/Util/Common/EscapeshellcmdTest.php
index 2844c4a320..213010de49 100644
--- a/tests/Core/Util/Common/EscapeshellcmdTest.php
+++ b/tests/Core/Util/Common/EscapeshellcmdTest.php
@@ -36,7 +36,7 @@ final class EscapeshellcmdTest extends TestCase
      */
     public function testEscapeshellcmd($command, $expected, $expectedWin=null)
     {
-        if (stripos(PHP_OS, 'WIN') === 0 && empty($expectedWin) === false) {
+        if (PHP_OS_FAMILY === 'Windows' && empty($expectedWin) === false) {
             $expected = $expectedWin;
         }