diff --git a/src/Service/Dfg3dViewerConfigApplier.php b/src/Service/Dfg3dViewerConfigApplier.php
index e88ec2c..165b3f4 100644
--- a/src/Service/Dfg3dViewerConfigApplier.php
+++ b/src/Service/Dfg3dViewerConfigApplier.php
@@ -3,7 +3,6 @@
 namespace Drupal\dfg_3dviewer\Service;
 
 use Drupal\Core\Config\ConfigFactoryInterface;
-use Drupal\Core\Config\ImmutableConfig;
 
 /**
  * Applies DFG 3D Viewer module settings to config storage.
@@ -125,7 +124,7 @@ class Dfg3dViewerConfigApplier {
   /**
    * Saves settings to config, mirroring the admin form submit behavior.
    */
-  public function apply(array $values): ImmutableConfig {
+  public function apply(array $values): void {
     $values = array_intersect_key($values, array_flip(self::SETTING_KEYS));
     $values = $this->prepareValues($values);
     $missing = $this->validateRequired($values);
@@ -138,8 +137,6 @@ class Dfg3dViewerConfigApplier {
       $settings->set($key, $value);
     }
     $settings->save();
-
-    return $settings;
   }
 
   /**