diff --git a/Core/README.md b/Core/README.md
index c6cc147..9910f5b 100644
--- a/Core/README.md
+++ b/Core/README.md
@@ -12,4 +12,4 @@ The folder contains all core files of "MOE". It includes MOE scheduler, MOE time
     Moe_Event  |   Event queue process.
     Moe_Queue  |   Provide easy-use queue services.
     Moe_HAL    |   Hardware Abstract Layer
-
+    Moe_PT     |   Protothread definition