diff -u b/core/includes/install.core.inc b/core/includes/install.core.inc
--- b/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -991,9 +991,6 @@
         ':input[name=driver]' => array('value' => $key),
       )
     );
-    if (!$driver->isCore()) {
-      $form['settings'][$key]['db_driver'] = array('#type' => 'value', '#value' => $key);
-    }
   }
 
   $form['actions'] = array('#type' => 'actions');
@@ -1021,6 +1018,10 @@
 function install_settings_form_validate($form, &$form_state) {
   $driver = $form_state['values']['driver'];
   $database = $form_state['values'][$driver];
+  $drivers = drupal_get_database_types();
+  if ($drivers[$driver]->isCustom()) {
+    $database['custom'] = TRUE;
+  }
   $database['driver'] = $driver;
 
   // TODO: remove when PIFR will be updated to use 'db_prefix' instead of
diff -u b/core/lib/Drupal/Core/Database/Connection.php b/core/lib/Drupal/Core/Database/Connection.php
--- b/core/lib/Drupal/Core/Database/Connection.php
+++ b/core/lib/Drupal/Core/Database/Connection.php
@@ -619,12 +619,11 @@
    */
   public function getDriverClass($class) {
     if (empty($this->driverClasses[$class])) {
-      if (isset($this->connectionOptions['db_driver'])) {
-        $driver = $this->connectionOptions['db_driver'];
+      $driver = $this->driver();
+      if (!empty($this->connectionOptions['custom'])) {
         $driver_class  = "Drupal\\{$driver}\\{$class}";
       }
       else {
-        $driver = $this->driver();
         $driver_class = "Drupal\\Core\\Database\\Driver\\{$driver}\\{$class}";
       }
       $this->driverClasses[$class] = class_exists($driver_class) ? $driver_class : $class;
diff -u b/core/lib/Drupal/Core/Database/Database.php b/core/lib/Drupal/Core/Database/Database.php
--- b/core/lib/Drupal/Core/Database/Database.php
+++ b/core/lib/Drupal/Core/Database/Database.php
@@ -369,19 +369,17 @@
     if (!isset(self::$databaseInfo[$key])) {
       throw new ConnectionNotDefinedException('The specified database connection is not defined: ' . $key);
     }
-
     if (!$driver = self::$databaseInfo[$key][$target]['driver']) {
       throw new DriverNotSpecifiedException('Driver not specified for this database connection: ' . $key);
     }
-    if (isset(self::$databaseInfo[$key][$target]['db_driver'])) {
-      $driver = self::$databaseInfo[$key][$target]['db_driver'];
+
+    if (!empty(self::$databaseInfo[$key][$target]['custom'])) {
       drupal_classloader_register($driver, "db_drivers/$driver");
-      $driver_namespace = 'Drupal';
+      $driver_class = "Drupal\\{$driver}\\Connection";
     }
     else {
-      $driver_namespace = 'Drupal\\Core\\Database\\Driver';
+      $driver_class = "Drupal\\Core\\Database\\Driver\\{$driver}\\Connection";
     }
-    $driver_class = "{$driver_namespace}\\{$driver}\\Connection";
     $new_connection = new $driver_class(self::$databaseInfo[$key][$target]);
     $new_connection->setTarget($target);
     $new_connection->setKey($key);
diff -u b/core/lib/Drupal/Core/Database/Install/Tasks.php b/core/lib/Drupal/Core/Database/Install/Tasks.php
--- b/core/lib/Drupal/Core/Database/Install/Tasks.php
+++ b/core/lib/Drupal/Core/Database/Install/Tasks.php
@@ -307,8 +307,8 @@
    *
    * @return
-   *   TRUE if this is a core driver, FALSE if the driver is in db_drivers.
+   *   TRUE if this is a custom driver, FALSE if the driver is in core.
    */
-  public function isCore() {
-    return TRUE;
+  public function isCustom() {
+    return FALSE;
   }
 }