diff --git a/typo3/sysext/core/Classes/Core/SystemEnvironmentBuilder.php b/typo3/sysext/core/Classes/Core/SystemEnvironmentBuilder.php
index e2a5a48f8bce1ed14f5673dc119fafce0324eee6..2ed868d234b56f8248401b7ab3783412a373d575 100644
--- a/typo3/sysext/core/Classes/Core/SystemEnvironmentBuilder.php
+++ b/typo3/sysext/core/Classes/Core/SystemEnvironmentBuilder.php
@@ -381,7 +381,7 @@ class SystemEnvironmentBuilder
         }
         // Find out if path is relative or not
         $isRelativePath = false;
-        if (TYPO3_OS === 'WIN') {
+        if (self::getTypo3Os() === 'WIN') {
             if (!preg_match('/^([a-zA-Z]:)?\\\\/', $scriptPath)) {
                 $isRelativePath = true;
             }
diff --git a/typo3/sysext/core/Documentation/Changelog/master/Deprecation-85285-DeprecatedSystemConstants.rst b/typo3/sysext/core/Documentation/Changelog/master/Deprecation-85285-DeprecatedSystemConstants.rst
index f45734c482d8be7ffdf535ce5736253c3f384e21..969228cfc972ee9f048cf32ae496782f6c122f55 100644
--- a/typo3/sysext/core/Documentation/Changelog/master/Deprecation-85285-DeprecatedSystemConstants.rst
+++ b/typo3/sysext/core/Documentation/Changelog/master/Deprecation-85285-DeprecatedSystemConstants.rst
@@ -23,6 +23,9 @@ The following constants have been deprecated and should not be used any longer:
 * :php:`PATH_typo3conf`
   Use :php:`Environment::getPublicPath() . '/typo3conf'` instead
 
+* :php:`TYPO3_OS`
+  Use :php:`Environment::isWindows()` and :php:`Environment::isUnix()` instead
+
 
 Impact
 ======
@@ -48,4 +51,4 @@ Migration
 Usages of the above constants should be switched to the Environment class methods instead.
 
 
-.. index:: PHP-API, FullyScanned
\ No newline at end of file
+.. index:: PHP-API, FullyScanned
diff --git a/typo3/sysext/core/Tests/Unit/Resource/ResourceCompressorTest.php b/typo3/sysext/core/Tests/Unit/Resource/ResourceCompressorTest.php
index 1f65b42f6fdbe7001c6f416a262b93ff258e5df4..404fdda093f434812b5d82deacf221376e05c9e2 100644
--- a/typo3/sysext/core/Tests/Unit/Resource/ResourceCompressorTest.php
+++ b/typo3/sysext/core/Tests/Unit/Resource/ResourceCompressorTest.php
@@ -618,7 +618,7 @@ class ResourceCompressorTest extends BaseTestCase
             Environment::getVarPath(),
             Environment::getConfigPath(),
             PATH_site . 'index.php',
-            TYPO3_OS === 'WIN' ? 'WINDOWS' : 'UNIX'
+            Environment::isWindows() ? 'WINDOWS' : 'UNIX'
         );
         $_SERVER['ORIG_SCRIPT_NAME'] = '/index.php';
         $this->subject = $this->getAccessibleMock(ResourceCompressor::class, ['dummy']);
diff --git a/typo3/sysext/install/Configuration/ExtensionScanner/Php/ConstantMatcher.php b/typo3/sysext/install/Configuration/ExtensionScanner/Php/ConstantMatcher.php
index c16ac744988a01a80c6b40d31448a665a8fe52cb..ec4f4a4b75a7100384ffb8fe961f3d728d642935 100644
--- a/typo3/sysext/install/Configuration/ExtensionScanner/Php/ConstantMatcher.php
+++ b/typo3/sysext/install/Configuration/ExtensionScanner/Php/ConstantMatcher.php
@@ -83,4 +83,10 @@ return [
             'Deprecation-85285-DeprecatedSystemConstants.rst',
         ],
     ],
+    'TYPO3_OS' => [
+        'restFiles' => [
+            'Feature-84153-IntroduceAGenericEnvironmentClass.rst',
+            'Deprecation-85285-DeprecatedSystemConstants.rst',
+        ],
+    ],
 ];