diff --git a/Classes/Context/Typo3Mode.php b/Classes/Context/Typo3Mode.php
new file mode 100644
index 00000000..84d7d764
--- /dev/null
+++ b/Classes/Context/Typo3Mode.php
@@ -0,0 +1,25 @@
+<?php
+declare(strict_types=1);
+
+namespace Brotkrueml\Schema\Context;
+
+class Typo3Mode
+{
+    /** @var string */
+    private $mode;
+
+    public function __construct()
+    {
+        $this->mode = \defined('TYPO3_MODE') ? TYPO3_MODE : '';
+    }
+
+    public function isInBackendMode(): bool
+    {
+        return $this->mode === 'BE';
+    }
+
+    public function isInFrontendMode(): bool
+    {
+        return $this->mode === 'FE';
+    }
+}
diff --git a/Classes/Hooks/PageRenderer/SchemaMarkupInjection.php b/Classes/Hooks/PageRenderer/SchemaMarkupInjection.php
index 9bb0ef37..3412c57f 100644
--- a/Classes/Hooks/PageRenderer/SchemaMarkupInjection.php
+++ b/Classes/Hooks/PageRenderer/SchemaMarkupInjection.php
@@ -11,6 +11,7 @@
 namespace Brotkrueml\Schema\Hooks\PageRenderer;
 
 use Brotkrueml\Schema\Aspect\AspectInterface;
+use Brotkrueml\Schema\Context\Typo3Mode;
 use Brotkrueml\Schema\Event\ShouldEmbedMarkupEvent;
 use Brotkrueml\Schema\Manager\SchemaManager;
 use TYPO3\CMS\Core\Cache\CacheManager;
@@ -39,6 +40,9 @@ final class SchemaMarkupInjection
     /** @var FrontendInterface */
     private $cache;
 
+    /** @var Typo3Mode */
+    private $typo3Mode;
+
     public function __construct(
         TypoScriptFrontendController $controller = null,
         ExtensionConfiguration $extensionConfiguration = null,
@@ -70,7 +74,7 @@ private function getCache(): ?FrontendInterface
 
     public function execute(?array &$params, PageRenderer &$pageRenderer): void
     {
-        if (TYPO3_MODE !== 'FE') {
+        if ($this->getTypo3Mode()->isInBackendMode()) {
             return;
         }
 
@@ -167,4 +171,22 @@ private function getRegisteredAspects(): array
 
         return $aspects;
     }
+
+    private function getTypo3Mode(): Typo3Mode
+    {
+        if (!$this->typo3Mode) {
+            $this->typo3Mode = new Typo3Mode();
+        }
+
+        return $this->typo3Mode;
+    }
+
+    /**
+     * @param Typo3Mode $typo3Mode
+     * @internal For testing purposes only!
+     */
+    public function setTypo3Mode(Typo3Mode $typo3Mode): void
+    {
+        $this->typo3Mode = $typo3Mode;
+    }
 }
diff --git a/Tests/Unit/Context/Typo3ModeTest.php b/Tests/Unit/Context/Typo3ModeTest.php
new file mode 100644
index 00000000..5d01be00
--- /dev/null
+++ b/Tests/Unit/Context/Typo3ModeTest.php
@@ -0,0 +1,88 @@
+<?php
+declare(strict_types=1);
+
+namespace Brotkrueml\Schema\Tests\Unit\Context;
+
+use Brotkrueml\Schema\Context\Typo3Mode;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @runTestsInSeparateProcesses
+ * @coversDefaultClass \Brotkrueml\Schema\Context\Typo3Mode
+ */
+class Typo3ModeTest extends TestCase
+{
+    /**
+     * @test
+     * @covers ::isInBackendMode
+     */
+    public function isInBackendModeReturnsFalseWhenConstantIsNotDefined(): void
+    {
+        $subject = new Typo3Mode();
+
+        self::assertFalse($subject->isInBackendMode());
+    }
+
+    /**
+     * @test
+     * @covers ::isInBackendMode
+     */
+    public function isInBackendModeReturnsFalseWhenConstantIsSetToFE(): void
+    {
+        \define('TYPO3_MODE', 'FE');
+
+        $subject = new Typo3Mode();
+
+        self::assertFalse($subject->isInBackendMode());
+    }
+
+    /**
+     * @test
+     * @covers ::isInBackendMode
+     */
+    public function isInBackendModeReturnsTrueWhenConstantIsSetToBE(): void
+    {
+        \define('TYPO3_MODE', 'BE');
+
+        $subject = new Typo3Mode();
+
+        self::assertTrue($subject->isInBackendMode());
+    }
+
+    /**
+     * @test
+     * @covers ::isInFrontendMode
+     */
+    public function isInFrontendModeReturnsFalseWhenConstantIsNotDefined(): void
+    {
+        $subject = new Typo3Mode();
+
+        self::assertFalse($subject->isInFrontendMode());
+    }
+
+    /**
+     * @test
+     * @covers ::isInFrontendMode
+     */
+    public function isInFrontendModeReturnsFalseWhenConstantIsSetToBE(): void
+    {
+        \define('TYPO3_MODE', 'BE');
+
+        $subject = new Typo3Mode();
+
+        self::assertFalse($subject->isInFrontendMode());
+    }
+
+    /**
+     * @test
+     * @covers ::isInFrontendMode
+     */
+    public function isInFrontendModeReturnsTrueWhenConstantIsSetToFE(): void
+    {
+        \define('TYPO3_MODE', 'FE');
+
+        $subject = new Typo3Mode();
+
+        self::assertTrue($subject->isInFrontendMode());
+    }
+}
diff --git a/Tests/Unit/Hooks/PageRenderer/SchemaMarkupInjectionTest.php b/Tests/Unit/Hooks/PageRenderer/SchemaMarkupInjectionTest.php
index 70cfc129..1fe551a8 100644
--- a/Tests/Unit/Hooks/PageRenderer/SchemaMarkupInjectionTest.php
+++ b/Tests/Unit/Hooks/PageRenderer/SchemaMarkupInjectionTest.php
@@ -10,11 +10,13 @@
 
 namespace Brotkrueml\Schema\Tests\Unit\Hooks\PageRenderer;
 
+use Brotkrueml\Schema\Context\Typo3Mode;
 use Brotkrueml\Schema\Hooks\PageRenderer\SchemaMarkupInjection;
 use Brotkrueml\Schema\Manager\SchemaManager;
 use Brotkrueml\Schema\Tests\Fixtures\Model\Type\FixtureThing;
 use Brotkrueml\Schema\Tests\Helper\SchemaCacheTrait;
 use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\MockObject\Stub;
 use PHPUnit\Framework\TestCase;
 use TYPO3\CMS\Core\Cache\Frontend\FrontendInterface;
 use TYPO3\CMS\Core\Configuration\ExtensionConfiguration;
@@ -66,6 +68,11 @@ class SchemaMarkupInjectionTest extends TestCase
      */
     private $signalSlotDispatcherMock;
 
+    /**
+     * @var Stub|Typo3Mode
+     */
+    private $typo3ModeStub;
+
     public static function setUpBeforeClass(): void
     {
         if (!\defined('TYPO3_version')) {
@@ -99,6 +106,10 @@ protected function setUp(): void
             $this->cacheMock
         );
 
+        $this->typo3ModeStub = $this->createStub(Typo3Mode::class);
+
+        $this->subject->setTypo3Mode($this->typo3ModeStub);
+
         $this->pageRendererMock = $this->createMock(PageRenderer::class);
 
         $this->signalSlotDispatcherMock = $this->createMock(Dispatcher::class);
@@ -125,7 +136,8 @@ protected function tearDown(): void
      */
     public function executeInBackendModeDoesNothing()
     {
-        $this->defineConstants('9.5', 'BE');
+        $this->defineConstants('9.5');
+
         $schemaManager = GeneralUtility::makeInstance(SchemaManager::class);
         $schemaManager->addType((new FixtureThing())->setProperty('name', 'some name'));
 
@@ -137,6 +149,10 @@ public function executeInBackendModeDoesNothing()
             ->expects(self::never())
             ->method('addFooterData');
 
+        $this->typo3ModeStub
+            ->method('isInBackendMode')
+            ->willReturn(true);
+
         $params = [];
         $this->subject->execute($params, $this->pageRendererMock);
     }
@@ -146,7 +162,7 @@ public function executeInBackendModeDoesNothing()
      */
     public function executeWithoutDefinedMarkupAndNoAspectsDoesNotEmbedAnything()
     {
-        $this->defineConstants('9.5', 'FE');
+        $this->defineConstants('9.5');
         $this->pageRendererMock
             ->expects(self::never())
             ->method('addHeaderData');
@@ -164,7 +180,7 @@ public function executeWithoutDefinedMarkupAndNoAspectsDoesNotEmbedAnything()
      */
     public function executeWithMarkupDefinedCallsAddHeaderDataIfShouldEmbeddedIntoHead(): void
     {
-        $this->defineConstants('9.5', 'FE');
+        $this->defineConstants('9.5');
 
         $schemaManager = GeneralUtility::makeInstance(SchemaManager::class);
         $schemaManager->addType((new FixtureThing())->setProperty('name', 'some name'));
@@ -200,7 +216,7 @@ public function executeWithMarkupDefinedCallsAddHeaderDataIfShouldEmbeddedIntoHe
      */
     public function executeWithSchemaCallsAddFooterDataOnceIfShouldEmbeddedIntoBody(): void
     {
-        $this->defineConstants('9.5', 'FE');
+        $this->defineConstants('9.5');
 
         $schemaManager = GeneralUtility::makeInstance(SchemaManager::class);
         $schemaManager->addType((new FixtureThing())->setProperty('name', 'some name'));
@@ -236,7 +252,7 @@ public function executeWithSchemaCallsAddFooterDataOnceIfShouldEmbeddedIntoBody(
      */
     public function seoExtensionIsNotInstalledAddsHeaderData(): void
     {
-        $this->defineConstants('9.5', 'FE');
+        $this->defineConstants('9.5');
 
         $controllerMock = $this->createMock(TypoScriptFrontendController::class);
         $controllerMock->page = ['uid' => 42];
@@ -271,7 +287,7 @@ public function seoExtensionIsNotInstalledAddsHeaderData(): void
      */
     public function whenCacheIDefinedItIsUsedToGetMarkup(): void
     {
-        $this->defineConstants('9.5', 'FE');
+        $this->defineConstants('9.5');
 
         $cacheMock = $this->createMock(FrontendInterface::class);
         $cacheMock
@@ -300,7 +316,7 @@ public function whenCacheIDefinedItIsUsedToGetMarkup(): void
      */
     public function whenCacheIsDefinedItIsUsedToStoreMarkup(): void
     {
-        $this->defineConstants('9.5', 'FE');
+        $this->defineConstants('9.5');
 
         $schemaManager = GeneralUtility::makeInstance(SchemaManager::class);
         $schemaManager->addType((new FixtureThing())->setProperty('name', 'some name'));
@@ -331,9 +347,8 @@ public function whenCacheIsDefinedItIsUsedToStoreMarkup(): void
         $subject->execute($params, $this->pageRendererMock);
     }
 
-    private function defineConstants(string $version, string $mode): void
+    private function defineConstants(string $version): void
     {
         \define('TYPO3_branch', $version);
-        \define('TYPO3_MODE', $mode);
     }
 }