diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
index 7be16b3..a000f4f 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
@@ -59,6 +59,7 @@ public static function open(array &$connection_options = array()) {
     }
     else {
       // Default to TCP connection on port 3306.
+      $connection_options['host'] = empty($connection_options['host']) ? 'localhost' : $connection_options['host'];
       $dsn = 'mysql:host=' . $connection_options['host'] . ';port=' . (empty($connection_options['port']) ? 3306 : $connection_options['port']);
     }
     if (!empty($connection_options['database'])) {
diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
index 68e9c98..1ae9c81 100644
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
@@ -77,7 +77,8 @@ public static function open(array &$connection_options = array()) {
       $connection_options['password'] = str_replace('\\', '\\\\', $connection_options['password']);
     }
 
-    $connection_options['database'] = (!empty($connection_options['database']) ? $connection_options['database'] : 'template1');
+    $connection_options['database'] = empty($connection_options['database']) ? 'template1' : $connection_options['database'];
+    $connection_options['host'] = empty($connection_options['host']) ? 'localhost' : $connection_options['host'];
     $dsn = 'pgsql:host=' . $connection_options['host'] . ' dbname=' . $connection_options['database'] . ' port=' . $connection_options['port'];
 
     // Allow PDO options to be overridden.