diff --git a/src/BusProNet/ApiResponseParser/MutableDataResponseParser.php b/src/BusProNet/ApiResponseParser/MutableDataResponseParser.php
index 305825b..aee351e 100644
--- a/src/BusProNet/ApiResponseParser/MutableDataResponseParser.php
+++ b/src/BusProNet/ApiResponseParser/MutableDataResponseParser.php
@@ -24,10 +24,10 @@ class MutableDataResponseParser
                 'unterbringung' => MutableData::CATEGORY_ACCOMMODATION,
                 'zusatzleistung' => MutableData::CATEGORY_ADDITIONAL_SERVICES,
                 'teilnehmerdaten' => MutableData::CATEGORY_PARTICIPANT_DATA,
-                default => false,
+                default => null,
             };
 
-            if (false === $category) {
+            if (null === $category) {
                 continue;
             }