diff --git a/CHANGELOG.md b/CHANGELOG.md
index 93ee874..e4dfd87 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,3 +3,7 @@
 - v0.1.0
     - first version.
     - The speed is no ideal as the data structures and backtrace algorithm are inefficient.
+- v0.2.0
+    - rewrite the whole package.
+    - more accurate.
+    - 2X faster than v0.1.0, lower memory.