diff --git a/src/DependencyInjection/NeustaConverterExtension.php b/src/DependencyInjection/NeustaConverterExtension.php
index 84380b7..33ff02c 100644
--- a/src/DependencyInjection/NeustaConverterExtension.php
+++ b/src/DependencyInjection/NeustaConverterExtension.php
@@ -39,6 +39,7 @@ private function registerConverterConfiguration(string $id, array $config, Conta
                 ->setArguments([
                     '$targetProperty' => $targetProperty,
                     '$sourceProperty' => $sourceProperty ?? $targetProperty,
+                    '$mapper' => null,
                     '$accessor' => new Reference('property_accessor'),
                 ]);
         }
@@ -49,6 +50,7 @@ private function registerConverterConfiguration(string $id, array $config, Conta
                 ->setArguments([
                     '$targetProperty' => $targetProperty,
                     '$sourceProperty' => $sourceProperty ?? $targetProperty,
+                    '$mapper' => null,
                     '$accessor' => new Reference('property_accessor'),
                 ]);
         }