diff --git a/src/Api/IMember.php b/src/Api/IMember.php
index 2b01bb8..9acbc4b 100644
--- a/src/Api/IMember.php
+++ b/src/Api/IMember.php
@@ -106,9 +106,9 @@ public function getName(): string;
 
     /**
      * Cast a value according to this class.
-     * @param  float|bool|int|string  $value The output to typecast.
-     * @return bool|int|float|string|SapDateTime|SapDateInterval
+     * @param  float|bool|int|string  $value  The output to typecast.
+     * @return null|bool|int|float|string|SapDateTime|SapDateInterval
      * @throws IInvalidArgumentException
      */
-    public function cast(bool|int|float|string $value): bool|int|float|string|SapDateTime|SapDateInterval;
+    public function cast(null|bool|int|float|string $value): null|bool|int|float|string|SapDateTime|SapDateInterval;
 }
diff --git a/src/Api/IValue.php b/src/Api/IValue.php
index 216452b..6f19e3f 100644
--- a/src/Api/IValue.php
+++ b/src/Api/IValue.php
@@ -142,8 +142,8 @@ public function isOptional(): bool;
     /**
      * Cast a given value according to this class.
      * @param  float|bool|int|string  $value The value to typecast.
-     * @return bool|int|float|string|SapDateTime|SapDateInterval
+     * @return null|bool|int|float|string|SapDateTime|SapDateInterval
      * @throws IInvalidArgumentException
      */
-    public function cast(bool|int|float|string $value): bool|int|float|string|SapDateTime|SapDateInterval;
+    public function cast(null|bool|int|float|string $value): null|bool|int|float|string|SapDateTime|SapDateInterval;
 }