diff --git a/src/SerializationMapper.php b/src/SerializationMapper.php
index 78d0c02ffc656ad97cb3184ac1d9412b75368805..a7a00cc009af4b52f460013363e877bc6baa60ca 100644
--- a/src/SerializationMapper.php
+++ b/src/SerializationMapper.php
@@ -170,7 +170,7 @@ final class SerializationMapper implements TypeFactoryInterface
         }
 
         if (!$classInfo->isInterface()) {
-            return BuiltinType::get('never');
+            throw new DomainException(sprintf('Cannot map %s', $resourceClass->getFullName()));
         }
 
         $parent = null;