diff -u b/core/includes/theme.inc b/core/includes/theme.inc
--- b/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1298,8 +1298,6 @@
   }
 
   if (empty($cache[$theme])) {
-    // Set the default values for each global setting.
-    $config = config('system.theme.global');
     // Provide defaults as function is used before config installed.
     $default_config = array(
       'favicon'  => array(
@@ -1319,11 +1317,10 @@
     foreach ($features as $feature) {
       $default_config['features'][$feature] = 1;
     }
-    $default_config = NestedArray::mergeDeep($default_config, $config->get());
 
     // Cache a config object that will merge $default_config,
     // system.theme configuration and the theme's config.
-    $cache[$theme] = clone $config;
+    $cache[$theme] = config('cache.' . $theme);
     $cache[$theme]->setData($default_config);
 
     // Get the values for the theme-specific settings from the .info files of
@@ -1341,12 +1338,16 @@
         $theme_keys = array($theme);
       }
       foreach ($theme_keys as $theme_key) {
-        // @todo Need to work how to convert this to CMI.
         if (!empty($themes[$theme_key]->info['settings'])) {
           $cache[$theme]->setData(NestedArray::mergeDeep($cache[$theme]->get(), $themes[$theme_key]->info['settings']));
         }
       }
+    }
+
+    // Get the saved global settings from the database.
+    $cache[$theme]->setData(NestedArray::mergeDeep($cache[$theme]->get(), config('system.theme.global')->get()));
 
+    if ($theme) {
       // Get the saved theme-specific settings from the configuration system.
       $cache[$theme]->setData(NestedArray::mergeDeep($cache[$theme]->get(), config($theme . '.settings')->get()));