diff --git a/src/Plugin/YamlFormElement/ManagedFile.php b/src/Plugin/YamlFormElement/ManagedFile.php
index a4a0024..28e9ff0 100644
--- a/src/Plugin/YamlFormElement/ManagedFile.php
+++ b/src/Plugin/YamlFormElement/ManagedFile.php
@@ -83,6 +83,14 @@ class ManagedFile extends YamlFormElementBase {
     $element['#upload_validators']['file_validate_size'] = [$this->getMaxFileSize($element)];
     $element['#upload_validators']['file_validate_extensions'] = [$this->getFileExtensions($element)];
     $element['#element_validate'][] = [get_class($this), 'validate'];
+
+
+    // Issue #2817535 by jrockowitz: Drupal file upload by anonymous or
+    // untrusted users into public file systems -- PSA-2016-003.
+    $stream_wrappers = self::getVisibleStreamWrappers();
+    if (!isset($element['#uri_scheme']) && isset($stream_wrappers['private'])) {
+      $element['#uri_scheme'] = 'private';
+    }
   }
 
   /**
@@ -97,13 +105,6 @@ class ManagedFile extends YamlFormElementBase {
       return;
     }
 
-    // Issue #2817535 by jrockowitz: Drupal file upload by anonymous or
-    // untrusted users into public file systems -- PSA-2016-003.
-    $stream_wrappers = self::getVisibleStreamWrappers();
-    if (!isset($element['#uri_scheme']) && isset($stream_wrappers['private'])) {
-      $element['#uri_scheme'] = 'private';
-    }
-
     $container = [
       '#prefix' => $element['#prefix'],
       '#suffix' => $element['#suffix'],