diff --git a/Classes/Configuration/TcaTweak.php b/Classes/Configuration/TcaTweak.php
index 14a1249..1df5d60 100644
--- a/Classes/Configuration/TcaTweak.php
+++ b/Classes/Configuration/TcaTweak.php
@@ -7,6 +7,8 @@
  * For the full copyright and license information, please read the
  * LICENSE.md file that was distributed with this source code.
  */
+
+use Psr\Http\Message\ServerRequestInterface;
 use TYPO3\CMS\Core\Http\ApplicationType;
 use Fab\Vidi\Tca\TcaServiceInterface;
 
@@ -93,12 +95,11 @@ protected function getForeignTable($dataType, $fieldName)
 
     /**
      * Returns whether the current mode is Frontend
-     *
-     * @return bool
      */
-    protected function isFrontendMode()
+    protected function isFrontendMode(): bool
     {
-        return ApplicationType::fromRequest($GLOBALS['TYPO3_REQUEST'])->isFrontend();
+        return ($GLOBALS['TYPO3_REQUEST'] ?? null) instanceof ServerRequestInterface
+            && ApplicationType::fromRequest($GLOBALS['TYPO3_REQUEST'])->isFrontend();
     }
 
 }