diff --git a/core/modules/config/lib/Drupal/config/Form/ConfigSingleImportForm.php b/core/modules/config/lib/Drupal/config/Form/ConfigSingleImportForm.php
index 24913c7..37d3293 100644
--- a/core/modules/config/lib/Drupal/config/Form/ConfigSingleImportForm.php
+++ b/core/modules/config/lib/Drupal/config/Form/ConfigSingleImportForm.php
@@ -206,7 +206,7 @@ public function validateForm(array &$form, array &$form_state) {
     }
     else {
       $config = $this->config($form_state['values']['config_name']);
-      $this->configExists = $config->isNew() ? $config : FALSE;
+      $this->configExists = !$config->isNew() ? $config : FALSE;
     }
 
     // Store the decoded version of the submitted import.
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigSingleImportExportTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigSingleImportExportTest.php
index 6d610a0..564218a 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigSingleImportExportTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigSingleImportExportTest.php
@@ -8,6 +8,7 @@
 namespace Drupal\config\Tests;
 
 use Drupal\simpletest\WebTestBase;
+use Symfony\Component\Yaml\Yaml;
 
 /**
  * Tests the user interface for importing/exporting a single configuration.
@@ -98,6 +99,25 @@ public function testImport() {
   }
 
   /**
+   * Tests importing a simple configuration file.
+   */
+  public function testImportSimpleConfiguration() {
+    $this->drupalLogin($this->drupalCreateUser(array('import configuration')));
+    $yaml = new Yaml();
+    $config = \Drupal::config('system.site')->set('name', 'Test simple import');
+    $edit = array(
+      'config_type' => 'system.simple',
+      'config_name' => $config->getName(),
+      'import' => $yaml->dump($config->get()),
+    );
+    $this->drupalPostForm('admin/config/development/configuration/single/import', $edit, t('Import'));
+    $this->assertRaw(t('Are you sure you want to update the %name @type?', array('%name' => $config->getName(), '@type' => 'simple configuration')));
+    $this->drupalPostForm(NULL, array(), t('Confirm'));
+    $this->drupalGet('/');
+    $this->assertText('Test simple import');
+  }
+
+  /**
    * Tests exporting a single configuration file.
    */
   public function testExport() {