diff --git a/docs/en/reference/custom-mapping-types.rst b/docs/en/reference/custom-mapping-types.rst
index 42367ae77..6f1ffbd3e 100644
--- a/docs/en/reference/custom-mapping-types.rst
+++ b/docs/en/reference/custom-mapping-types.rst
@@ -43,8 +43,8 @@ a ``DateTimeImmutable`` when the data is read from the database.
 
         public function convertToDatabaseValue($value): array
         {
-            if (! is_array($value) || ! isset($value['utc'], $value['tz'])) {
-                throw new Exception(); // TODO: throw correct exception class
+            if (! isset($value['utc'], $value['tz'])) {
+                throw new RuntimeException('Database value cannot be converted to date with timezone. Expected array with "utc" and "tz" keys.');
             }
 
             return [
diff --git a/tests/Documentation/CustomMapping/DateTimeWithTimezoneType.php b/tests/Documentation/CustomMapping/DateTimeWithTimezoneType.php
index 429b837d8..39e2395a0 100644
--- a/tests/Documentation/CustomMapping/DateTimeWithTimezoneType.php
+++ b/tests/Documentation/CustomMapping/DateTimeWithTimezoneType.php
@@ -10,6 +10,7 @@
 use Doctrine\ODM\MongoDB\Types\ClosureToPHP;
 use Doctrine\ODM\MongoDB\Types\Type;
 use MongoDB\BSON\UTCDateTime;
+use RuntimeException;
 
 class DateTimeWithTimezoneType extends Type
 {
@@ -19,6 +20,10 @@ class DateTimeWithTimezoneType extends Type
     /** @param array{utc: UTCDateTime, tz: string} $value */
     public function convertToPHPValue($value): DateTimeImmutable
     {
+        if (! isset($value['utc'], $value['tz'])) {
+            throw new RuntimeException('Database value cannot be converted to date with timezone. Expected array with "utc" and "tz" keys.');
+        }
+
         $timeZone = new DateTimeZone($value['tz']);
         $dateTime = $value['utc']
             ->toDateTime()