diff --git a/src/ExternalLibrary/Exception/InvalidLibraryDependencyException.php b/src/ExternalLibrary/Exception/InvalidLibraryDependencyException.php
index a3c33530f68a050c08a64a7519dfb02a996b3cf5..004691eac47c9602268b4475f37924512e22f427 100644
--- a/src/ExternalLibrary/Exception/InvalidLibraryDependencyException.php
+++ b/src/ExternalLibrary/Exception/InvalidLibraryDependencyException.php
@@ -6,9 +6,9 @@
  */
 
 namespace Drupal\libraries\ExternalLibrary\Exception;
-use Drupal\libraries\ExternalLibrary\DependencyAccessorTrait;
+use Drupal\libraries\ExternalLibrary\Utility\DependencyAccessorTrait;
 use Drupal\libraries\ExternalLibrary\ExternalLibraryInterface;
-use Drupal\libraries\ExternalLibrary\LibraryAccessorTrait;
+use Drupal\libraries\ExternalLibrary\Utility\LibraryAccessorTrait;
 
 /**
  *
diff --git a/src/ExternalLibrary/Exception/LibraryClassNotFoundException.php b/src/ExternalLibrary/Exception/LibraryClassNotFoundException.php
index aadfaef04389c4dd877e18248a6c82023cb72dd5..000fa5de8d7707bfe030da81274f42adf378d142 100644
--- a/src/ExternalLibrary/Exception/LibraryClassNotFoundException.php
+++ b/src/ExternalLibrary/Exception/LibraryClassNotFoundException.php
@@ -6,7 +6,8 @@
  */
 
 namespace Drupal\libraries\ExternalLibrary\Exception;
-use Drupal\libraries\ExternalLibrary\LibraryIdAccessorTrait;
+
+use Drupal\libraries\ExternalLibrary\Utility\LibraryIdAccessorTrait;
 use Exception;
 
 /**
diff --git a/src/ExternalLibrary/Exception/LibraryDefinitionNotFoundException.php b/src/ExternalLibrary/Exception/LibraryDefinitionNotFoundException.php
index 53ebfe0b756b497309bbbccb1d09f64e1d3a6958..80621f9e3eb333643a9c94c4df5bfd08ab54fc41 100644
--- a/src/ExternalLibrary/Exception/LibraryDefinitionNotFoundException.php
+++ b/src/ExternalLibrary/Exception/LibraryDefinitionNotFoundException.php
@@ -6,7 +6,8 @@
  */
 
 namespace Drupal\libraries\ExternalLibrary\Exception;
-use Drupal\libraries\ExternalLibrary\LibraryIdAccessorTrait;
+
+use Drupal\libraries\ExternalLibrary\Utility\LibraryIdAccessorTrait;
 use Exception;
 
 /**
diff --git a/src/ExternalLibrary/Registry/ExternalLibraryRegistry.php b/src/ExternalLibrary/Registry/ExternalLibraryRegistry.php
index 0c59a641b64cedd013fda5ba4cdbadf3f04dc92c..b31cea867a5ed8517b516ecb4d2a95a66f923ae4 100644
--- a/src/ExternalLibrary/Registry/ExternalLibraryRegistry.php
+++ b/src/ExternalLibrary/Registry/ExternalLibraryRegistry.php
@@ -44,7 +44,7 @@ class ExternalLibraryRegistry implements ExternalLibraryRegistryInterface {
       throw new LibraryDefinitionNotFoundException($id);
     }
     $definition = $this->getDefinition($id);
-    $class = $this->getClass($definition);
+    $class = $this->getClass($id, $definition);
     return $class::create($id, $definition);
   }
 
@@ -91,6 +91,8 @@ class ExternalLibraryRegistry implements ExternalLibraryRegistryInterface {
   /**
    * Returns the library class for a library definition.
    *
+   * @param string $id
+   *   The ID of the external library.
    * @param array $definition
    *   The library definition array parsed from the definition JSON file.
    *
@@ -99,11 +101,10 @@ class ExternalLibraryRegistry implements ExternalLibraryRegistryInterface {
    *
    * @throws \Drupal\libraries\ExternalLibrary\Exception\LibraryClassNotFoundException
    */
-  protected function getClass(array $definition) {
+  protected function getClass($id, array $definition) {
     // @todo Reconsider
     if (!isset($definition['class'])) {
-      // @todo What if $definition['id'] is not set?
-      throw new LibraryClassNotFoundException($definition['id']);
+      throw new LibraryClassNotFoundException($id);
     }
     // @todo Make sure the class exists.
     return $definition['class'];
diff --git a/src/StreamWrapper/PhpLibraryFilesStream.php b/src/StreamWrapper/PhpLibraryFilesStream.php
index abfcbb752b60afa75b124927e1296b2c4297c578..a05a37289a5064263c0bfb228dda6987b1a1b67c 100644
--- a/src/StreamWrapper/PhpLibraryFilesStream.php
+++ b/src/StreamWrapper/PhpLibraryFilesStream.php
@@ -39,6 +39,7 @@ class PhpLibraryFilesStream extends LocalStream {
    * {@inheritdoc}
    */
   public function getDirectoryPath() {
+    // @todo Provide support for site-specific directories, etc.
     return 'sites/all/libraries';
   }