diff --git a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperManager.php b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperManager.php
index e5b65e8..d8de07f 100644
--- a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperManager.php
+++ b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperManager.php
@@ -120,6 +120,9 @@ public function getWrappers($filter = STREAM_WRAPPERS_ALL) {
    */
   public function processDefinition(&$definition, $plugin_id) {
     parent::processDefinition($definition, $plugin_id);
+    if (!isset($definition['type'])) {
+      $definition['type'] = STREAM_WRAPPERS_NORMAL;
+    }
 
     // Record whether we are overriding an existing scheme.
     if (in_array($plugin_id, stream_get_wrappers(), TRUE)) {