diff --git a/framework/YiiBase.php b/framework/YiiBase.php
index faf8a6e..1a3f50c 100644
--- a/framework/YiiBase.php
+++ b/framework/YiiBase.php
@@ -370,7 +370,8 @@ class YiiBase
 
 		include($classFile);
 
-		if (class_exists($className, false) || interface_exists($className, false)) {
+		if (class_exists($className, false) || interface_exists($className, false) ||
+			function_exists('trait_exists') && trait_exists($className, false)) {
 			return true;
 		} else {
 			throw new UnknownClassException("Unable to find '$className' in file: $classFile");