diff --git a/CHANGELOG.md b/CHANGELOG.md
index 16baacd..0f1d0db 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## 0.5.1
 
 * Support Symfony 7
+* Fix service definition for MapperFactory
 
 ## 0.5.0
 
diff --git a/config/services.php b/config/services.php
index 8a13594..1aaf505 100644
--- a/config/services.php
+++ b/config/services.php
@@ -119,7 +119,7 @@
         ->set('rekalogika.mapper.type_string_helper', TypeStringHelper::class)
 
         ->set('rekalogika.mapper.mapping_factory', MappingFactory::class)
-            ->args([tagged_iterator('rekalogika.mapper.transformer')])
+            ->args([tagged_iterator('rekalogika.mapper.transformer', 'key')])
 
         ->alias(MappingFactoryInterface::class, 'rekalogika.mapper.mapping_factory')