diff --git a/core/ClassInfo.php b/core/ClassInfo.php
index e1e3d5a18..503df0bab 100644
--- a/core/ClassInfo.php
+++ b/core/ClassInfo.php
@@ -12,16 +12,16 @@ class ClassInfo {
 	 * @todo Improve documentation
 	 */
 	static function allClasses() {
-		global $_ALL_CLASSES;
-		return $_ALL_CLASSES['exists'];
+		global $_CLASS_MANIFEST;
+		return ArrayLib::valuekey(array_keys($_CLASS_MANIFEST));
 	}
 
 	/**
 	 * @todo Improve documentation
 	 */
 	static function exists($class) {
-		global $_ALL_CLASSES;
-		return isset($_ALL_CLASSES['exists'][$class]) ? $_ALL_CLASSES['exists'][$class] : null;
+		global $_CLASS_MANIFEST;
+		return class_exists($class, false) || array_key_exists(strtolower($class), $_CLASS_MANIFEST);
 	}
 
 	/**
diff --git a/tests/ClassInfoTest.php b/tests/ClassInfoTest.php
index bc3c49daa..53d261ef4 100644
--- a/tests/ClassInfoTest.php
+++ b/tests/ClassInfoTest.php
@@ -4,7 +4,13 @@
  * @subpackage tests
  */
 class ClassInfoTest extends SapphireTest {
-	
+
+	public function testExists() {
+		$this->assertTrue(ClassInfo::exists('Object'));
+		$this->assertTrue(ClassInfo::exists('ClassInfoTest'));
+		$this->assertTrue(ClassInfo::exists('stdClass'));
+	}
+
 	function testSubclassesFor() {
 		$this->assertEquals(
 			ClassInfo::subclassesFor('ClassInfoTest_BaseClass'),