diff --git a/core/lib/Drupal/Core/Config/TypedConfigManager.php b/core/lib/Drupal/Core/Config/TypedConfigManager.php
index 631dc5c..896b08e 100644
--- a/core/lib/Drupal/Core/Config/TypedConfigManager.php
+++ b/core/lib/Drupal/Core/Config/TypedConfigManager.php
@@ -150,6 +150,7 @@ public function getDefinition($base_plugin_id) {
       $definition = NestedArray::mergeDeep($merge, $definition);
       // Unset type so we try the merge only once per type.
       unset($definition['type']);
+      $this->definitions[$type] = $definition;
     }
     return $definition;
   }