diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
index ea26c10..3ba7356 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Schema.php
@@ -9,6 +9,7 @@
 
 use Drupal\Core\Database\Database;
 use Drupal\Core\Database\Query\Condition;
+use Drupal\Core\Database\SchemaIndexNotInSpecException;
 use Drupal\Core\Database\SchemaObjectExistsException;
 use Drupal\Core\Database\SchemaObjectDoesNotExistException;
 use Drupal\Core\Database\Schema as DatabaseSchema;
diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
index 301466c..4b6d131 100644
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php
@@ -8,6 +8,7 @@
 namespace Drupal\Core\Database\Driver\sqlite;
 
 use Drupal\Component\Utility\Unicode;
+use Drupal\Core\Database\SchemaIndexNotInSpecException;
 use Drupal\Core\Database\SchemaObjectExistsException;
 use Drupal\Core\Database\SchemaObjectDoesNotExistException;
 use Drupal\Core\Database\Schema as DatabaseSchema;
diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
index 6f433f8..60eb9fe 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
@@ -1140,7 +1140,7 @@ protected function createSharedTableSchema(FieldStorageDefinitionInterface $stor
                 // Check if the index exists because it might already have been
                 // created as part of the earlier entity type update event.
                 if (!$schema_handler->indexExists($table_name, $name)) {
-                  $schema_handler->addNormalizedIndex($table_name, $name, $schema);
+                  $schema_handler->addNormalizedIndex($table_name, $name, $schema[$table_name]);
                 }
               }
             }
@@ -1383,7 +1383,7 @@ protected function updateSharedTableSchema(FieldStorageDefinitionInterface $stor
             // Create new indexes and unique keys.
             if (!empty($schema[$table_name]['indexes'])) {
               foreach ($schema[$table_name]['indexes'] as $name => $specifier) {
-                $schema_handler->addNormalizedIndex($table_name, $name, $schema);
+                $schema_handler->addNormalizedIndex($table_name, $name, $schema[$table_name]);
               }
             }
             if (!empty($schema[$table_name]['unique keys'])) {
diff --git a/core/modules/system/src/Tests/Database/SchemaTest.php b/core/modules/system/src/Tests/Database/SchemaTest.php
index 910d44c..1bd2b06 100644
--- a/core/modules/system/src/Tests/Database/SchemaTest.php
+++ b/core/modules/system/src/Tests/Database/SchemaTest.php
@@ -297,7 +297,7 @@ function testIndexLength() {
 
     // Add a separate index.
     $table_specification_new = $table_specification;
-    $table_specification_new['indexes']['test_separate'] = array('test_field_text', 200);
+    $table_specification_new['indexes']['test_separate'] = [['test_field_text', 200]];
     Database::getConnection()->schema()->addNormalizedIndex('test_table_index_length', 'test_separate', $table_specification_new);
 
     // Get index information.
@@ -328,7 +328,7 @@ function testIndexLength() {
 
     // Count the number of columns defined in the indexes.
     $column_count = 0;
-    foreach ($table_specification['indexes'] as $index) {
+    foreach ($table_specification_new['indexes'] as $index) {
       foreach ($index as $field) {
         $column_count++;
       }