diff --git a/core/config/schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
index d75df89..a3b6c62 100644
--- a/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
@@ -29,6 +29,9 @@ ignore:
   class: '\Drupal\Core\Config\Schema\Ignore'
 
 # Container data types with lists with known and uknown keys.
+sequence:
+  label: Sequence
+  class: '\Drupal\Core\Config\Schema\Sequence'
 mapping:
   label: Mapping
   class: '\Drupal\Core\Config\Schema\Mapping'