diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
index b1aa8f7..688ff79 100644
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php
@@ -421,8 +421,11 @@ function renameTable($table, $new_name) {
     // rename them when renaming the table.
     $indexes = $this->connection->query('SELECT indexname FROM pg_indexes WHERE schemaname = :schema AND tablename = :table', array(':schema' => $old_schema, ':table' => $old_table_name));
     foreach ($indexes as $index) {
-      if (preg_match('/^' . preg_quote($old_full_name) . '_(.*)$/', $index->indexname, $matches)) {
-        $index_name = $matches[1];
+      if (preg_match('/^' . preg_quote($old_full_name) . '__(.*)$/', $index->indexname, $matches)) {
+        // Remove the '__idx' suffix from index name, because
+        // $this->ensureIdentifiersLength() will add the __idx suffix again and
+        // thus would result in a wrong index name.
+        $index_name = substr($matches[1], 0, -5);
         $this->connection->query('ALTER INDEX ' . $index->indexname . ' RENAME TO ' . $this->ensureIdentifiersLength($new_name, $index_name, 'idx'));
       }
     }