diff --git a/core/modules/file/lib/Drupal/file/FileStorage.php b/core/modules/file/lib/Drupal/file/FileStorage.php
index ab6c148..2c83913 100644
--- a/core/modules/file/lib/Drupal/file/FileStorage.php
+++ b/core/modules/file/lib/Drupal/file/FileStorage.php
@@ -50,7 +50,10 @@ protected function buildSchema() {
       'file__changed' => array('changed'),
     );
     $schema['file_managed']['unique keys'] += array(
-      'file__uri' => array('uri'),
+      // FIXME We are raising the index size from 255 to 333, but the max URI
+      // length is 2048 so this might now always work. Should we replace this
+      // with a regular index?
+      'file__uri' => array(array('uri', 333)),
     );
 
     $schema['file_usage'] = array(