diff --git a/index.php b/index.php
index ba6b408..f2a5d98 100644
--- a/index.php
+++ b/index.php
@@ -20,24 +20,14 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-namespace OCC\OAI2;
+use OCC\OAI2\Exception;
+use OCC\OAI2\Server;
 
-// Register autoloader
-spl_autoload_register(function ($class) {
-    $base_dir = __DIR__.'/Classes/';
-    $len = strlen(__NAMESPACE__);
-    if (strncmp(__NAMESPACE__, $class, $len) !== 0) {
-        return;
-    }
-    $relative_class = substr($class, $len);
-    $file = $base_dir.str_replace('\\', '/', $relative_class).'.php';
-    if (file_exists($file)) {
-        require $file;
-    }
-});
+// Register PSR-4 autoloader
+require __DIR__.'/vendor/autoload.php';
 
 // Load configuration
-require './Configuration/Main.php';
+require __DIR__.'/Configuration/Main.php';
 
 // Get all available records and their respective status and timestamps
 $records = [];
diff --git a/update.php b/update.php
index b9dc80b..3a9f4f9 100644
--- a/update.php
+++ b/update.php
@@ -22,7 +22,7 @@ if (php_sapi_name() !== 'cli') {
     exit;
 }
 
-require './Configuration/Main.php';
+require __DIR__.'/Configuration/Main.php';
 
 /**
  * Format output string
@@ -71,7 +71,7 @@ $sourceDir = rtrim($sourceDir, '/').'/';
 // Prepend script's path if dataDir is not an absolute path
 $dataDir = rtrim($config['dataDirectory'], '/').'/'.$metadataPrefix.'/';
 if (strpos($dataDir, '/') !== 0) {
-    $dataDir = dirname(__FILE__).'/'.$dataDir;
+    $dataDir = __DIR__.'/'.$dataDir;
 }
 // Check dataDir permissions
 if (!is_dir($dataDir) || !is_writable($dataDir)) {