diff -u b/core/lib/Drupal/Core/Asset/LibraryDiscovery.php b/core/lib/Drupal/Core/Asset/LibraryDiscovery.php
--- b/core/lib/Drupal/Core/Asset/LibraryDiscovery.php
+++ b/core/lib/Drupal/Core/Asset/LibraryDiscovery.php
@@ -106,7 +106,7 @@
    * {@inheritdoc}
    */
   public function clearCachedDefinitions() {
-    $this->cacheTagInvalidator->invalidateTags(['library_discovery']);
+    $this->cacheTagInvalidator->invalidateTags(['library_info']);
   }
 
 }
diff -u b/core/lib/Drupal/Core/Asset/LibraryDiscoveryCollector.php b/core/lib/Drupal/Core/Asset/LibraryDiscoveryCollector.php
--- b/core/lib/Drupal/Core/Asset/LibraryDiscoveryCollector.php
+++ b/core/lib/Drupal/Core/Asset/LibraryDiscoveryCollector.php
@@ -17,7 +17,13 @@
  */
 class LibraryDiscoveryCollector extends CacheCollector {
 
+  /**
+   * The cache key.
+   *
+   * @var string
+   */
   protected $cid;
+
   /**
    * The cache backend.
    *
@@ -60,8 +66,8 @@
    */
   public function __construct(CacheBackendInterface $cache, LockBackendInterface $lock, LibraryDiscoveryParser $discovery_parser, ThemeManagerInterface $theme_manager) {
     $this->themeManager = $theme_manager;
-    $this->cid = 'library_discovery:' . $this->themeManager->getActiveTheme()->getName();
-    parent::__construct($this->cid, $cache, $lock, ['library_discovery']);
+    $this->cid = 'library_info:' . $this->themeManager->getActiveTheme()->getName();
+    parent::__construct($this->cid, $cache, $lock, ['library_info']);
 
     $this->discoveryParser = $discovery_parser;
   }
diff -u b/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryTest.php b/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryTest.php
--- b/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryTest.php
+++ b/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryTest.php
@@ -43,7 +43,7 @@
    * @var \Drupal\Core\Theme\ThemeManagerInterface|\PHPUnit_Framework_MockObject_MockObject
    */
   protected $themeManager;
- 
+
   /**
    * The cache tags invalidator.
    *
only in patch2:
unchanged:
--- a/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryCollectorTest.php
+++ b/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryCollectorTest.php
@@ -41,6 +41,13 @@ class LibraryDiscoveryCollectorTest extends UnitTestCase {
   protected $libraryDiscoveryCollector;
 
   /**
+   * The mocked theme manager.
+   *
+   * @var \Drupal\Core\Theme\ThemeManagerInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $themeManager;
+
+  /**
    * Test library data.
    *
    * @var array
@@ -56,17 +63,21 @@ class LibraryDiscoveryCollectorTest extends UnitTestCase {
     ),
   );
 
+  protected $activeTheme;
+
   /**
    * {@inheritdoc}
    */
   protected function setUp() {
     $this->cache = $this->getMock('Drupal\Core\Cache\CacheBackendInterface');
     $this->lock = $this->getMock('Drupal\Core\Lock\LockBackendInterface');
+    $this->themeManager = $this->getMockBuilder('Drupal\Core\Theme\ThemeManagerInterface')
+      ->disableOriginalConstructor()
+      ->getMock();
     $this->libraryDiscoveryParser = $this->getMockBuilder('Drupal\Core\Asset\LibraryDiscoveryParser')
       ->disableOriginalConstructor()
       ->getMock();
 
-    $this->libraryDiscoveryCollector = new LibraryDiscoveryCollector($this->cache, $this->lock, $this->libraryDiscoveryParser);
   }
 
   /**
@@ -75,6 +86,17 @@ protected function setUp() {
    * @covers ::resolveCacheMiss
    */
   public function testResolveCacheMiss() {
+    $this->activeTheme = $this->getMockBuilder('Drupal\Core\Theme\ActiveTheme')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $this->themeManager->expects($this->once())
+      ->method('getActiveTheme')
+      ->will($this->returnValue($this->activeTheme));
+    $this->activeTheme->expects($this->once())
+      ->method('getName')
+      ->will($this->returnValue('kitten_theme'));
+    $this->libraryDiscoveryCollector = new LibraryDiscoveryCollector($this->cache, $this->lock, $this->libraryDiscoveryParser, $this->themeManager);
+
     $this->libraryDiscoveryParser->expects($this->once())
       ->method('buildByExtension')
       ->with('test')
@@ -90,12 +112,23 @@ public function testResolveCacheMiss() {
    * @covers ::destruct
    */
   public function testDestruct() {
+    $this->activeTheme = $this->getMockBuilder('Drupal\Core\Theme\ActiveTheme')
+      ->disableOriginalConstructor()
+      ->getMock();
+    $this->themeManager->expects($this->once())
+      ->method('getActiveTheme')
+      ->will($this->returnValue($this->activeTheme));
+    $this->activeTheme->expects($this->once())
+      ->method('getName')
+      ->will($this->returnValue('kitten_theme'));
+    $this->libraryDiscoveryCollector = new LibraryDiscoveryCollector($this->cache, $this->lock, $this->libraryDiscoveryParser, $this->themeManager);
+
     $this->libraryDiscoveryParser->expects($this->once())
       ->method('buildByExtension')
       ->with('test')
       ->will($this->returnValue($this->libraryData));
 
-    $lock_key = 'library_info:Drupal\Core\Cache\CacheCollector';
+    $lock_key = 'library_info:kitten_theme:Drupal\Core\Cache\CacheCollector';
 
     $this->lock->expects($this->once())
       ->method('acquire')
@@ -103,11 +136,11 @@ public function testDestruct() {
       ->will($this->returnValue(TRUE));
     $this->cache->expects($this->exactly(2))
       ->method('get')
-      ->with('library_info')
+      ->with('library_info:kitten_theme')
       ->will($this->returnValue(FALSE));
     $this->cache->expects($this->once())
       ->method('set')
-      ->with('library_info', array('test' => $this->libraryData), Cache::PERMANENT, array('library_info'));
+      ->with('library_info:kitten_theme', array('test' => $this->libraryData), Cache::PERMANENT, ['library_info']);
     $this->lock->expects($this->once())
       ->method('release')
       ->with($lock_key);