diff --git a/README.md b/README.md
index 6ec20f97a..43af362f3 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ gitter](https://gitter.im/ethereum/sharding).
 
 ## TODO:
 
-- [ ] Implement crystallized state.
+- [x] Implement crystallized state.
 - [ ] Implement state transition.
 - [ ] Implement integration tests (some unit tests are implemented now).
 - [ ] Implement RLP serialization across-the-board.