diff --git a/src/Symfony/Component/Debug/DebugClassLoader.php b/src/Symfony/Component/Debug/DebugClassLoader.php
index 603c814b56..2230231c8a 100644
--- a/src/Symfony/Component/Debug/DebugClassLoader.php
+++ b/src/Symfony/Component/Debug/DebugClassLoader.php
@@ -186,7 +186,7 @@ class DebugClassLoader
 
         $exists = class_exists($class, false) || interface_exists($class, false) || (function_exists('trait_exists') && trait_exists($class, false));
 
-        if ('\\' === $class[0]) {
+        if ($class !== '' && '\\' === $class[0]) {
             $class = substr($class, 1);
         }