diff --git a/src/Symfony/Component/Console/Helper/SymfonyQuestionHelper.php b/src/Symfony/Component/Console/Helper/SymfonyQuestionHelper.php
index fd9b703fc1..01f94aba4b 100644
--- a/src/Symfony/Component/Console/Helper/SymfonyQuestionHelper.php
+++ b/src/Symfony/Component/Console/Helper/SymfonyQuestionHelper.php
@@ -100,7 +100,7 @@ class SymfonyQuestionHelper extends QuestionHelper
 
     private function getEofShortcut(): string
     {
-        if (false !== strpos(\PHP_OS, 'WIN')) {
+        if ('Windows' === \PHP_OS_FAMILY) {
             return '<comment>Ctrl+Z</comment> then <comment>Enter</comment>';
         }
 
diff --git a/src/Symfony/Component/Console/Tests/Helper/SymfonyQuestionHelperTest.php b/src/Symfony/Component/Console/Tests/Helper/SymfonyQuestionHelperTest.php
index b57ac1d602..ed08008523 100644
--- a/src/Symfony/Component/Console/Tests/Helper/SymfonyQuestionHelperTest.php
+++ b/src/Symfony/Component/Console/Tests/Helper/SymfonyQuestionHelperTest.php
@@ -218,7 +218,7 @@ EOT
     {
         $expected = 'Write an essay (press Ctrl+D to continue)';
 
-        if (false !== strpos(\PHP_OS, 'WIN')) {
+        if ('Windows' === \PHP_OS_FAMILY) {
             $expected = 'Write an essay (press Ctrl+Z then Enter to continue)';
         }
 
diff --git a/src/Symfony/Component/ErrorHandler/DebugClassLoader.php b/src/Symfony/Component/ErrorHandler/DebugClassLoader.php
index 561f9b5740..1f49692f72 100644
--- a/src/Symfony/Component/ErrorHandler/DebugClassLoader.php
+++ b/src/Symfony/Component/ErrorHandler/DebugClassLoader.php
@@ -208,7 +208,7 @@ class DebugClassLoader
             } elseif (substr($test, -\strlen($file)) === $file) {
                 // filesystem is case insensitive and realpath() normalizes the case of characters
                 self::$caseCheck = 1;
-            } elseif (false !== stripos(\PHP_OS, 'darwin')) {
+            } elseif ('Darwin' === \PHP_OS_FAMILY) {
                 // on MacOSX, HFS+ is case insensitive but realpath() doesn't normalize the case of characters
                 self::$caseCheck = 2;
             } else {