diff --git a/includes/module.inc b/includes/module.inc
index 2e25108..a068569 100644
--- a/includes/module.inc
+++ b/includes/module.inc
@@ -193,8 +193,11 @@ function system_list($type) {
           foreach (array_keys($lists['theme'][$key]->base_themes) as $base_theme) {
             $lists['theme'][$base_theme]->sub_themes[$key] = $lists['theme'][$key]->info['name'];
           }
-          // Add the base theme's theme engine info.
-          $lists['theme'][$key]->info['engine'] = isset($lists['theme'][$base_key]->info['engine']) ? $lists['theme'][$base_key]->info['engine'] : 'theme';
+          // Add the base theme's theme engine info only when subtheme does not
+          // define one, this allows to use different theme engines.
+          if (!isset($lists['theme'][$key]->info['engine'])) {
+            $lists['theme'][$key]->info['engine'] = isset($lists['theme'][$base_key]->info['engine']) ? $lists['theme'][$base_key]->info['engine'] : 'theme';
+          }
         }
         else {
           // A plain theme is its own engine.
diff --git a/includes/theme.inc b/includes/theme.inc
index 9b606e9..05ea943 100644
--- a/includes/theme.inc
+++ b/includes/theme.inc
@@ -139,7 +139,7 @@ function drupal_theme_initialize() {
  *   The callback to invoke to set the theme registry.
  */
 function _drupal_theme_initialize($theme, $base_theme = array(), $registry_callback = '_theme_load_registry') {
-  global $theme_info, $base_theme_info, $theme_engine, $theme_path;
+  global $theme_info, $base_theme_info, $theme_path;
   $theme_info = $theme;
   $base_theme_info = $base_theme;
 
@@ -201,37 +201,28 @@ function _drupal_theme_initialize($theme, $base_theme = array(), $registry_callb
     drupal_add_js($script, array('group' => JS_THEME, 'every_page' => TRUE));
   }
 
-  $theme_engine = NULL;
-
-  // Initialize the theme.
-  if (isset($theme->engine)) {
-    // Include the engine.
-    include_once DRUPAL_ROOT . '/' . $theme->owner;
+  // Initialize all themes and engines.
+  // Make sure we do not load the same theme engine twice.
+  $theme_init = array();
+  foreach (list_themes() as $current) {
+    $key = $current->owner . ' ' . $current->engine;
+    if (isset($theme_init[$key])) {
+      continue;
+    }
 
-    $theme_engine = $theme->engine;
-    if (function_exists($theme_engine . '_init')) {
-      foreach ($base_theme as $base) {
-        call_user_func($theme_engine . '_init', $base);
-      }
-      call_user_func($theme_engine . '_init', $theme);
+    if (isset($current->owner)) {
+      include_once DRUPAL_ROOT . '/' . $current->owner;
     }
-  }
-  else {
-    // include non-engine theme files
-    foreach ($base_theme as $base) {
-      // Include the theme file or the engine.
-      if (!empty($base->owner)) {
-        include_once DRUPAL_ROOT . '/' . $base->owner;
+    if (isset($current->engine)) {
+      if (function_exists($current->engine . '_init')) {
+        call_user_func($current->engine . '_init', $current);
       }
     }
-    // and our theme gets one too.
-    if (!empty($theme->owner)) {
-      include_once DRUPAL_ROOT . '/' . $theme->owner;
-    }
+    $theme_init[$key] = $current;
   }
 
   if (isset($registry_callback)) {
-    _theme_registry_callback($registry_callback, array($theme, $base_theme, $theme_engine));
+    _theme_registry_callback($registry_callback, array($theme, $base_theme));
   }
 }
 
@@ -304,8 +295,6 @@ function _theme_registry_callback($callback = NULL, array $arguments = array())
  * @param $base_theme
  *   An array of loaded $theme objects representing the ancestor themes in
  *   oldest first order.
- * @param $theme_engine
- *   The name of the theme engine.
  * @param $complete
  *   Whether to load the complete theme registry or an instance of the
  *   ThemeRegistry class.
@@ -313,7 +302,7 @@ function _theme_registry_callback($callback = NULL, array $arguments = array())
  * @return
  *   The theme registry array, or an instance of the ThemeRegistry class.
  */
-function _theme_load_registry($theme, $base_theme = NULL, $theme_engine = NULL, $complete = TRUE) {
+function _theme_load_registry($theme, $base_theme = NULL, $complete = TRUE) {
   if ($complete) {
     // Check the theme registry cache; if it exists, use it.
     $cached = cache_get("theme_registry:$theme->name");
@@ -322,7 +311,7 @@ function _theme_load_registry($theme, $base_theme = NULL, $theme_engine = NULL,
     }
     else {
       // If not, build one and cache it.
-      $registry = _theme_build_registry($theme, $base_theme, $theme_engine);
+      $registry = _theme_build_registry($theme, $base_theme);
       // Only persist this registry if all modules are loaded. This assures a
       // complete set of theme hooks.
       if (module_load_all(NULL)) {
@@ -672,10 +661,8 @@ function _theme_process_registry(&$cache, $name, $type, $theme, $path) {
  * @param $base_theme
  *   An array of loaded $theme objects representing the ancestor themes in
  *   oldest first order.
- * @param $theme_engine
- *   The name of the theme engine.
  */
-function _theme_build_registry($theme, $base_theme, $theme_engine) {
+function _theme_build_registry($theme, $base_theme) {
   $cache = array();
   // First, process the theme hooks advertised by modules. This will
   // serve as the basic registry. Since the list of enabled modules is the same
@@ -698,15 +685,15 @@ function _theme_build_registry($theme, $base_theme, $theme_engine) {
   foreach ($base_theme as $base) {
     // If the base theme uses a theme engine, process its hooks.
     $base_path = dirname($base->filename);
-    if ($theme_engine) {
-      _theme_process_registry($cache, $theme_engine, 'base_theme_engine', $base->name, $base_path);
+    if (isset($base->engine)) {
+      _theme_process_registry($cache, $base->engine, 'base_theme_engine', $base->name, $base_path);
     }
     _theme_process_registry($cache, $base->name, 'base_theme', $base->name, $base_path);
   }
 
   // And then the same thing, but for the theme.
-  if ($theme_engine) {
-    _theme_process_registry($cache, $theme_engine, 'theme_engine', $theme->name, dirname($theme->filename));
+  if (isset($theme->engine)) {
+    _theme_process_registry($cache, $theme->engine, 'theme_engine', $theme->name, dirname($theme->filename));
   }
 
   // Finally, hooks provided by the theme itself.
@@ -1167,8 +1154,8 @@ function theme($hook, $variables = array()) {
     $extension = '.tpl.php';
 
     // The theme engine may use a different extension and a different renderer.
-    global $theme_engine;
-    if (isset($theme_engine)) {
+    if (isset($info['engine'])) {
+      $theme_engine = $info['engine'];
       if ($info['type'] != 'module') {
         if (function_exists($theme_engine . '_render_template')) {
           $render_function = $theme_engine . '_render_template';
@@ -1309,10 +1296,21 @@ function drupal_find_theme_templates($cache, $extension, $path) {
   // used for filtering. This allows base themes to have sub-themes in its
   // folder hierarchy without affecting the base themes template discovery.
   $theme_paths = array();
-  foreach (list_themes() as $theme_info) {
+  $current_theme = NULL;
+  $current_engine = NULL;
+  foreach (list_themes() as $key => $theme_info) {
     if (!empty($theme_info->base_theme)) {
       $theme_paths[$theme_info->base_theme][$theme_info->name] = dirname($theme_info->filename);
     }
+    $theme_path = dirname($theme_info->filename);
+    if ($path === $theme_path) {
+      $current_theme = $current_theme;
+      $current_engine = isset($theme_info->engine) ? $theme_info->engine : NULL;
+    }
+    else if (!$current_theme && 0 === strpos($theme_path, $current_theme)) {
+      $current_theme = $current_theme;
+      $current_engine = isset($theme_info->engine) ? $theme_info->engine : NULL;
+    }
   }
   foreach ($theme_paths as $basetheme => $subthemes) {
     foreach ($subthemes as $subtheme => $subtheme_path) {
@@ -1349,6 +1347,7 @@ function drupal_find_theme_templates($cache, $extension, $path) {
     if (isset($cache[$hook])) {
       $implementations[$hook] = array(
         'template' => $template,
+        'engine' => $current_engine,
         'path' => dirname($file->uri),
       );
     }
@@ -1375,6 +1374,7 @@ function drupal_find_theme_templates($cache, $extension, $path) {
           $arg_name = isset($info['variables']) ? 'variables' : 'render element';
           $implementations[strtr($file, '-', '_')] = array(
             'template' => $file,
+            'engine' => $current_engine,
             'path' => dirname($files[$match]->uri),
             $arg_name => $info[$arg_name],
             'base hook' => $hook,
diff --git a/includes/theme.maintenance.inc b/includes/theme.maintenance.inc
index 6baf219..df8d446 100644
--- a/includes/theme.maintenance.inc
+++ b/includes/theme.maintenance.inc
@@ -87,8 +87,8 @@ function _drupal_maintenance_theme() {
 /**
  * Builds the registry when the site needs to bypass any database calls.
  */
-function _theme_load_offline_registry($theme, $base_theme = NULL, $theme_engine = NULL) {
-  return _theme_build_registry($theme, $base_theme, $theme_engine);
+function _theme_load_offline_registry($theme, $base_theme = NULL) {
+  return _theme_build_registry($theme, $base_theme);
 }
 
 /**
diff --git a/modules/system/system.module b/modules/system/system.module
index 59087c8..c988f3b 100644
--- a/modules/system/system.module
+++ b/modules/system/system.module
@@ -2606,12 +2606,12 @@ function _system_rebuild_theme_data() {
       $themes[$base_theme]->sub_themes[$key] = $themes[$key]->info['name'];
     }
     // Copy the 'owner' and 'engine' over if the top level theme uses a theme
-    // engine.
-    if (isset($themes[$base_key]->owner)) {
+    // engine and the current theme has no engine itself.
+    if (isset($themes[$base_key]->owner) && !isset($themes[$key]->owner)) {
       if (isset($themes[$base_key]->info['engine'])) {
-        $themes[$key]->info['engine'] = $themes[$base_key]->info['engine'];
-        $themes[$key]->owner = $themes[$base_key]->owner;
-        $themes[$key]->prefix = $themes[$base_key]->prefix;
+         $themes[$key]->info['engine'] = $themes[$base_key]->info['engine'];
+         $themes[$key]->owner = $themes[$base_key]->owner;
+         $themes[$key]->prefix = $themes[$base_key]->prefix;
       }
       else {
         $themes[$key]->prefix = $key;