diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 7d638f6..e8d704c 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -60,8 +60,7 @@ function drupal_theme_access($theme) {
  * @see drupal_theme_access()
  */
 function _drupal_theme_access($theme) {
-  $admin_theme = variable_get('admin_theme');
-  return !empty($theme->status) || ($admin_theme && $theme->name == $admin_theme);
+  return !empty($theme->status);
 }
 
 /**
diff --git a/core/modules/block/block.module b/core/modules/block/block.module
index 97f59e9..b0ee304 100644
--- a/core/modules/block/block.module
+++ b/core/modules/block/block.module
@@ -177,7 +177,7 @@ function block_menu() {
 }
 
 /**
- * Access callback: Only admin or enabled themes can be accessed.
+ * Access callback: Only enabled themes can be accessed.
  *
  * Path:
  * - admin/structure/block/list/% (for each theme)
diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockAdminThemeTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockAdminThemeTest.php
deleted file mode 100644
index 0397802..0000000
--- a/core/modules/block/lib/Drupal/block/Tests/BlockAdminThemeTest.php
+++ /dev/null
@@ -1,46 +0,0 @@
-<?php
-
-/**
- * @file
- * Definition of Drupal\block\Tests\BlockAdminThemeTest.
- */
-
-namespace Drupal\block\Tests;
-
-use Drupal\simpletest\WebTestBase;
-
-/**
- * Test the block system with admin themes.
- */
-class BlockAdminThemeTest extends WebTestBase {
-  public static function getInfo() {
-    return array(
-      'name' => 'Admin theme block admin accessibility',
-      'description' => "Check whether the block administer page for a disabled theme accessible if and only if it's the admin theme.",
-      'group' => 'Block',
-    );
-  }
-
-  function setUp() {
-    parent::setUp(array('block'));
-  }
-
-  /**
-   * Check for the accessibility of the admin theme on the  block admin page.
-   */
-  function testAdminTheme() {
-    // Create administrative user.
-    $admin_user = $this->drupalCreateUser(array('administer blocks', 'administer themes'));
-    $this->drupalLogin($admin_user);
-
-    // Ensure that access to block admin page is denied when theme is disabled.
-    $this->drupalGet('admin/structure/block/list/bartik');
-    $this->assertResponse(403, t('The block admin page for a disabled theme can not be accessed'));
-
-    // Enable admin theme and confirm that tab is accessible.
-    $edit['admin_theme'] = 'bartik';
-    $this->drupalPost('admin/appearance', $edit, t('Save configuration'));
-    $this->drupalGet('admin/structure/block/list/bartik');
-    $this->assertResponse(200, t('The block admin page for the admin theme can be accessed'));
-  }
-}
diff --git a/core/modules/block/lib/Drupal/block/Tests/DisabledBlockAdminTest.php b/core/modules/block/lib/Drupal/block/Tests/DisabledBlockAdminTest.php
new file mode 100644
index 0000000..3ab8f33
--- /dev/null
+++ b/core/modules/block/lib/Drupal/block/Tests/DisabledBlockAdminTest.php
@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\block\Tests\DisabledBlockAdminTest.
+ */
+
+namespace Drupal\block\Tests;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Test the block system with admin themes.
+ */
+class DisabledBlockAdminTest extends WebTestBase {
+  public static function getInfo() {
+    return array(
+      'name' => 'Disabled theme admin',
+      'description' => "Check the administer page for disabled theme.",
+      'group' => 'Block',
+    );
+  }
+
+  function setUp() {
+    parent::setUp(array('block'));
+  }
+
+  /**
+   * Check for the accessibility of the admin theme on the  block admin page.
+   */
+  function testAdminTheme() {
+    // Create administrative user.
+    $admin_user = $this->drupalCreateUser(array('administer blocks', 'administer themes'));
+    $this->drupalLogin($admin_user);
+
+    // Ensure that access to block admin page is denied when theme is disabled.
+    $this->drupalGet('admin/structure/block/list/bartik');
+    $this->assertResponse(403, t('The block admin page for a disabled theme can not be accessed.'));
+  }
+}
diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index a31e278..da0444a 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -117,12 +117,12 @@ function system_themes_page() {
 
   $theme_default = variable_get('theme_default', 'stark');
   $theme_groups  = array();
+  $admin_theme = variable_get('admin_theme', 0);
 
   foreach ($themes as &$theme) {
     if (!empty($theme->info['hidden'])) {
       continue;
     }
-    $admin_theme_options[$theme->name] = $theme->info['name'];
     $theme->is_default = ($theme->name == $theme_default);
 
     // Identify theme screenshot.
@@ -169,12 +169,14 @@ function system_themes_page() {
       }
       if (!empty($theme->status)) {
         if (!$theme->is_default) {
-          $theme->operations[] = array(
-            'title' => t('Disable'),
-            'href' => 'admin/appearance/disable',
-            'query' => $query,
-            'attributes' => array('title' => t('Disable !theme theme', array('!theme' => $theme->info['name']))),
-          );
+          if ($theme->name != $admin_theme) {
+            $theme->operations[] = array(
+              'title' => t('Disable'),
+              'href' => 'admin/appearance/disable',
+              'query' => $query,
+              'attributes' => array('title' => t('Disable !theme theme', array('!theme' => $theme->info['name']))),
+            );
+          }
           $theme->operations[] = array(
             'title' => t('Set default'),
             'href' => 'admin/appearance/default',
@@ -182,6 +184,7 @@ function system_themes_page() {
             'attributes' => array('title' => t('Set !theme as default theme', array('!theme' => $theme->info['name']))),
           );
         }
+        $admin_theme_options[$theme->name] = $theme->info['name'];
       }
       else {
         $theme->operations[] = array(
@@ -206,6 +209,9 @@ function system_themes_page() {
       $theme->classes[] = 'theme-default';
       $theme->notes[] = t('default theme');
     }
+    if ($theme->name == $admin_theme || ($theme->is_default && $admin_theme == '0')) {
+      $theme->notes[] = t('admin theme');
+    }
 
     // Sort enabled and disabled themes into their own groups.
     $theme_groups[$theme->status ? 'enabled' : 'disabled'][] = $theme;
@@ -294,7 +300,7 @@ function system_theme_disable() {
 
     // Check if the specified theme is one recognized by the system.
     if (!empty($themes[$theme])) {
-      if ($theme == variable_get('theme_default', 'stark')) {
+      if ($theme == variable_get('theme_default', 'stark') || $theme == variable_get('admin_theme', 0)) {
         // Don't disable the default theme.
         drupal_set_message(t('%theme is the default theme and cannot be disabled.', array('%theme' => $themes[$theme]->info['name'])), 'error');
       }
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 5394830..bcc44d1 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -1779,7 +1779,7 @@ function blocked_ip_load($iid) {
 }
 
 /**
- * Menu item access callback - only admin or enabled themes can be accessed.
+ * Menu item access callback - only enabled themes can be accessed.
  */
 function _system_themes_access($theme) {
   return user_access('administer themes') && drupal_theme_access($theme);
diff --git a/core/modules/system/system.test b/core/modules/system/system.test
index 9d25130..a44423b 100644
--- a/core/modules/system/system.test
+++ b/core/modules/system/system.test
@@ -1870,6 +1870,9 @@ class SystemThemeFunctionalTest extends WebTestBase {
   function testAdministrationTheme() {
     theme_enable(array('stark'));
     variable_set('theme_default', 'stark');
+
+    // Make seven available as a theme option.
+    theme_enable(array('seven'));
     // Enable an administration theme and show it on the node admin pages.
     $edit = array(
       'admin_theme' => 'seven',
diff --git a/core/modules/system/tests/batch.test b/core/modules/system/tests/batch.test
index e39bcf5..77aeae5 100644
--- a/core/modules/system/tests/batch.test
+++ b/core/modules/system/tests/batch.test
@@ -301,6 +301,7 @@ class BatchPageTestCase extends WebTestBase {
     // Make sure that the page which starts the batch (an administrative page)
     // is using a different theme than would normally be used by the batch API.
     variable_set('theme_default', 'bartik');
+    theme_enable(array('seven'));
     variable_set('admin_theme', 'seven');
     // Log in as an administrator who can see the administrative theme.
     $admin_user = $this->drupalCreateUser(array('view the administration theme'));
diff --git a/core/modules/system/tests/menu.test b/core/modules/system/tests/menu.test
index dbd94a1..bf6fdd3 100644
--- a/core/modules/system/tests/menu.test
+++ b/core/modules/system/tests/menu.test
@@ -187,6 +187,7 @@ class MenuRouterTestCase extends WebTestBase {
    * Test the theme callback when it is set to use an administrative theme.
    */
   function testThemeCallbackAdministrative() {
+    theme_enable(array('seven'));
     $this->drupalGet('menu-test/theme-callback/use-admin-theme');
     $this->assertText('Custom theme: seven. Actual theme: seven.', t('The administrative theme can be correctly set in a theme callback.'));
     $this->assertRaw('seven/style.css', t("The administrative theme's CSS appears on the page."));
@@ -196,6 +197,7 @@ class MenuRouterTestCase extends WebTestBase {
    * Test that the theme callback is properly inherited.
    */
   function testThemeCallbackInheritance() {
+    theme_enable(array('seven'));
     $this->drupalGet('menu-test/theme-callback/use-admin-theme/inheritance');
     $this->assertText('Custom theme: seven. Actual theme: seven. Theme callback inheritance is being tested.', t('Theme callback inheritance correctly uses the administrative theme.'));
     $this->assertRaw('seven/style.css', t("The administrative theme's CSS appears on the page."));
@@ -226,6 +228,7 @@ class MenuRouterTestCase extends WebTestBase {
    */
   function testThemeCallbackMaintenanceMode() {
     variable_set('maintenance_mode', TRUE);
+    theme_enable(array('seven'));
 
     // For a regular user, the fact that the site is in maintenance mode means
     // we expect the theme callback system to be bypassed entirely.
@@ -330,6 +333,7 @@ class MenuRouterTestCase extends WebTestBase {
     // the requested page.
     variable_set('menu_test_hook_custom_theme_name', 'stark');
     theme_enable(array('stark'));
+    theme_enable(array('seven'));
 
     // The menu "theme callback" should take precedence over a value set in
     // hook_custom_theme().
diff --git a/core/modules/taxonomy/taxonomy.test b/core/modules/taxonomy/taxonomy.test
index c7e87e8..c44083f 100644
--- a/core/modules/taxonomy/taxonomy.test
+++ b/core/modules/taxonomy/taxonomy.test
@@ -1901,6 +1901,7 @@ class TaxonomyThemeTestCase extends TaxonomyWebTestCase {
   function testTaxonomyTermThemes() {
     // Adding a term to a vocabulary is considered an administrative action and
     // should use the administrative theme.
+    theme_enable(array('seven'));
     $vocabulary = $this->createVocabulary();
     $this->drupalGet('admin/structure/taxonomy/' . $vocabulary->machine_name . '/add');
     $this->assertRaw('seven/style.css', t("The administrative theme's CSS appears on the page for adding a taxonomy term."));