diff --git a/core/modules/responsive_image/src/ResponsiveImageStyleForm.php b/core/modules/responsive_image/src/ResponsiveImageStyleForm.php
index bceb596..c01a03b 100644
--- a/core/modules/responsive_image/src/ResponsiveImageStyleForm.php
+++ b/core/modules/responsive_image/src/ResponsiveImageStyleForm.php
@@ -181,9 +181,6 @@ public function validate(array $form, FormStateInterface $form_state) {
         // Remove the image style mappings since the breakpoint ID has changed.
         $form_state->unsetValue('keyed_styles');
       }
-      // @todo Filter 'sizes_image_styles' to a normal array in
-      // https://www.drupal.org/node/2334387. For an example see
-      // \Drupal\Core\Block\BlockBase::validateConfigurationForm().
     }
   }
 
@@ -203,7 +200,7 @@ public function save(array $form, FormStateInterface $form_state) {
               'image_mapping_type' => 'sizes',
               'image_mapping' => array(
                 'sizes' => $image_style_mapping['sizes'],
-                'sizes_image_styles' => $image_style_mapping['sizes_image_styles'],
+                'sizes_image_styles' => array_filter($image_style_mapping['sizes_image_styles']),
               )
             );
             $responsive_image_style->addImageStyleMapping($breakpoint_id, $multiplier, $mapping);