diff --git a/whatsmars-common/README.md b/whatsmars-common/README.md
index 6a7f1902..ddc93444 100644
--- a/whatsmars-common/README.md
+++ b/whatsmars-common/README.md
@@ -26,6 +26,8 @@
 
 |----------------util
 
+|------------------collections
+
 |------------------concurrent
 
 |------------------function