diff --git a/core/lib/Drupal/Core/Asset/AssetLibraryRepository.php b/core/lib/Drupal/Core/Asset/AssetLibraryRepository.php
index 95a2cb3..5c6b3aa 100644
--- a/core/lib/Drupal/Core/Asset/AssetLibraryRepository.php
+++ b/core/lib/Drupal/Core/Asset/AssetLibraryRepository.php
@@ -27,17 +27,17 @@ class AssetLibraryRepository {
    *
    * @var
    */
-  protected $collector;
+  protected $factory;
 
-  function __construct(AssetLibraryFactory $collector) {
-    $this->collector = $collector;
+  function __construct(AssetLibraryFactory $factory) {
+    $this->factory = $factory;
   }
 
   /**
    * Gets a library by its composite key.
    *
    * @param string $key
-   *   The key of the library, as a string of the form "$module:$name".
+   *   The key of the library, as a string of the form "$module/$name".
    *
    * @return \Drupal\Core\Asset\Collection\AssetLibrary
    *   The requested library.
@@ -50,7 +50,7 @@ public function get($key) {
       return $this->libraries[$key];
     }
 
-    if ($library = $this->collector->getLibrary($key)) {
+    if ($library = $this->factory->getLibrary($key)) {
       $this->set($key, $library);
     }
     else {
@@ -61,10 +61,10 @@ public function get($key) {
   }
 
   public function set($key, AssetLibrary $library) {
-    if (preg_match('/[^0-9A-Za-z:_-]/', $key)) {
+    if (preg_match('/[^0-9A-Za-z\/_-]/', $key)) {
       throw new \InvalidArgumentException(sprintf('The name "%s" is invalid.', $key));
     }
-    elseif (substr_count($key, ':') !== 1) {
+    elseif (substr_count($key, '/') !== 1) {
       throw new \InvalidArgumentException(sprintf('Invalid key "%s" provided; asset libraries must have exactly one colon in their key, separating the owning module from the library name.', $key));
     }
 
@@ -79,7 +79,7 @@ public function set($key, AssetLibrary $library) {
    * created already.
    *
    * @param string $key
-   *   The key of the library, as a string of the form "$module:$name".
+   *   The key of the library, as a string of the form "$module/$name".
    *
    * @return bool
    *   TRUE if the library has been built, FALSE otherwise.
diff --git a/core/lib/Drupal/Core/Asset/Factory/AssetLibraryFactory.php b/core/lib/Drupal/Core/Asset/Factory/AssetLibraryFactory.php
index 41bd488..f8ba302 100644
--- a/core/lib/Drupal/Core/Asset/Factory/AssetLibraryFactory.php
+++ b/core/lib/Drupal/Core/Asset/Factory/AssetLibraryFactory.php
@@ -6,8 +6,6 @@
 
 namespace Drupal\Core\Asset\Factory;
 
-use Drupal\Component\Utility\Crypt;
-use \Drupal\Core\Asset\AssetLibraryRepository;
 use Drupal\Core\Asset\Factory\AssetCollector;
 use Drupal\Core\Asset\Collection\AssetLibrary;
 use Drupal\Core\Asset\Metadata\DefaultAssetMetadataFactory;
@@ -74,7 +72,7 @@ public function __construct(ModuleHandlerInterface $moduleHandler, AssetCollecto
    *   data.
    */
   public function getLibrary($key) {
-    list($module, $name) = preg_split('/:/', $key);
+    list($module, $name) = preg_split('/\//', $key);
 
     if (!$this->moduleHandler->implementsHook($module, 'library_info')) {
       // Module doesn't implement hook_library_info(), a library can't exist.
diff --git a/core/tests/Drupal/Tests/Core/Asset/AssetLibraryRepositoryTest.php b/core/tests/Drupal/Tests/Core/Asset/AssetLibraryRepositoryTest.php
index 599878f..5642bc8 100644
--- a/core/tests/Drupal/Tests/Core/Asset/AssetLibraryRepositoryTest.php
+++ b/core/tests/Drupal/Tests/Core/Asset/AssetLibraryRepositoryTest.php
@@ -56,7 +56,7 @@ public function createAssetLibraryRepository() {
       ->with('library_info')
       ->will($this->returnValue(array('stub1', 'stub2')));
 
-    $factory = $this->getMock('\\Drupal\\Core\\Asset\\Factory\\AssetLibraryFactory', $module_handler);
+    $factory = $this->getMock('\\Drupal\\Core\\Asset\\Factory\\AssetLibraryFactory', array(), array($module_handler));
     return new AssetLibraryRepository($factory);
   }
 
@@ -66,7 +66,7 @@ public function createAssetLibraryRepository() {
   public function testSet() {
     $repository = $this->createAssetLibraryRepository();
     $library = $this->getMock('\\Drupal\\Core\\Asset\\Collection\\AssetLibrary');
-    $repository->set('foo:bar', $library);
+    $repository->set('foo/bar', $library);
 
     $this->assertAttributeContains($library, 'libraries', $repository);
   }
@@ -86,11 +86,11 @@ public function testSetNoColon() {
    * @covers ::set
    * @expectedException \InvalidArgumentException
    */
-  public function testSetTooManyColons() {
+  public function testSetTooManySlashes() {
     $repository = $this->createAssetLibraryRepository();
     $library = $this->getMock('\\Drupal\\Core\\Asset\\Collection\\AssetLibrary');
 
-    $repository->set('foo::bar', $library);
+    $repository->set('foo//bar', $library);
   }
 
   /**
@@ -101,7 +101,7 @@ public function testSetInvalidKeyChars() {
     $repository = $this->createAssetLibraryRepository();
     $library = $this->getMock('\\Drupal\\Core\\Asset\\Collection\\AssetLibrary');
 
-    $repository->set("$∫≤ˆ\"'\n\t\r", $library);
+    $repository->set("\$∫≤:ˆ\"'\n\t\r", $library);
   }
 
   /**
@@ -112,10 +112,10 @@ public function testHas() {
     $repository = $this->createAssetLibraryRepository();
     $library = $this->getMock('\\Drupal\\Core\\Asset\\Collection\\AssetLibrary');
 
-    $this->assertFalse($repository->has('foo:bar'));
+    $this->assertFalse($repository->has('foo/bar'));
 
-    $repository->set('foo:bar', $library);
-    $this->assertTrue($repository->has('foo:bar'));
+    $repository->set('foo/bar', $library);
+    $this->assertTrue($repository->has('foo/bar'));
   }
 
   /**
@@ -126,10 +126,10 @@ public function testGetNames() {
     $repository = $this->createAssetLibraryRepository();
     $library = $this->getMock('\\Drupal\\Core\\Asset\\Collection\\AssetLibrary');
 
-    $repository->set('foo:bar', $library);
-    $repository->set('baz:bing', $library);
+    $repository->set('foo/bar', $library);
+    $repository->set('baz/bing', $library);
 
-    $this->assertEquals(array('foo:bar', 'baz:bing'), $repository->getNames());
+    $this->assertEquals(array('foo/bar', 'baz/bing'), $repository->getNames());
   }
 
   /**
@@ -138,14 +138,14 @@ public function testGetNames() {
    */
   public function testGet() {
     $library = $this->getMock('\\Drupal\\Core\\Asset\\Collection\\AssetLibrary');
-    $factory = $this->getMock('\\Drupal\\Core\\Asset\\Factory\\AssetLibraryFactory');
+    $factory = $this->getMock('\\Drupal\\Core\\Asset\\Factory\\AssetLibraryFactory', array(), array(), '', FALSE);
     $factory->expects($this->once())
       ->method('getLibrary')
-      ->with($this->equalTo('foo:bar'))
+      ->with($this->equalTo('foo/bar'))
       ->will($this->returnValue($library));
 
     $repository = new AssetLibraryRepository($factory);
-    $this->assertSame($library, $repository->get('foo:bar'));
+    $this->assertSame($library, $repository->get('foo/bar'));
   }
 }
 
diff --git a/core/tests/Drupal/Tests/Core/Asset/Factory/AssetLibraryFactoryTest.php b/core/tests/Drupal/Tests/Core/Asset/Factory/AssetLibraryFactoryTest.php
index cd9443c..30aa78a 100644
--- a/core/tests/Drupal/Tests/Core/Asset/Factory/AssetLibraryFactoryTest.php
+++ b/core/tests/Drupal/Tests/Core/Asset/Factory/AssetLibraryFactoryTest.php
@@ -71,9 +71,9 @@ public function testGetLibrary() {
     $collector = $this->getMock('\\Drupal\\Core\\Asset\\Factory\\AssetCollector');
     $factory = new AssetLibraryFactory($module_handler, $collector);
 
-    $this->assertFalse($factory->getLibrary('stub1:foo'));
+    $this->assertFalse($factory->getLibrary('stub1/foo'));
 
-    $lib1 = $factory->getLibrary('stub1:solo-nodeps-js');
+    $lib1 = $factory->getLibrary('stub1/solo-nodeps-js');
 
     $this->assertInstanceOf('\\Drupal\\Core\\Asset\\Collection\\AssetLibrary', $lib1);
     $this->assertEquals('solo-nodeps-js', $lib1->getTitle());
@@ -81,7 +81,7 @@ public function testGetLibrary() {
     $this->assertEquals('http://foo.bar', $lib1->getWebsite());
     $this->assertTrue($lib1->isFrozen());
 
-    $lib2 = $factory->getLibrary('stub1:solo-onedep-same');
+    $lib2 = $factory->getLibrary('stub1/solo-onedep-same');
 
     $this->assertInstanceOf('\\Drupal\\Core\\Asset\\Collection\\AssetLibrary', $lib2);
     $this->assertEquals(array(array('stub1', 'solo-nodeps-js')), $lib2->getDependencyInfo());
@@ -100,7 +100,7 @@ public function testGetLibraryModuleDoesNotImplementHook() {
     $collector = $this->getMock('\\Drupal\\Core\\Asset\\Factory\\AssetCollector');
     $factory = new AssetLibraryFactory($module_handler, $collector);
 
-    $this->assertFalse($factory->getLibrary('foo:bar'));
+    $this->assertFalse($factory->getLibrary('foo/bar'));
   }
 }