diff --git a/Classes/Controller/AbstractController.php b/Classes/Controller/AbstractController.php
index cc617ad09..496cc4d90 100644
--- a/Classes/Controller/AbstractController.php
+++ b/Classes/Controller/AbstractController.php
@@ -259,7 +259,7 @@ protected function sanitizeRequestData(): void
         }
 
         // tx_dlf[double] may only be 0 or 1.
-        $this->requestData['double'] = MathUtility::forceIntegerInRange($this->requestData['double'], 0, 1, 0);
+        $this->requestData['double'] = MathUtility::forceIntegerInRange($this->requestData['double'] ?? 0, 0, 1);
     }
 
     /**