diff --git a/src/DependencyInjection/Configuration.php b/src/DependencyInjection/Configuration.php
index 5a93fab..43b768f 100644
--- a/src/DependencyInjection/Configuration.php
+++ b/src/DependencyInjection/Configuration.php
@@ -263,6 +263,7 @@ private function setupSimpleOptions(ArrayNodeDefinition $node): void
     {
         $node->children()
             ->scalarNode('image_processor')
+                ->defaultNull()
                 ->info('The image processor to use to generate the icons of different sizes.')
                 ->example(GDImageProcessor::class)
             ->end()