diff --git a/Cargo.toml b/Cargo.toml
index e69a999..9118561 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,7 +2,7 @@
 name = "ckb-merkle-mountain-range"
 version = "0.6.0"
 authors = ["Nervos Core Dev <dev@nervos.org>"]
-edition = "2018"
+edition = "2021"
 rust-version = "1.60.0"
 license = "MIT"
 description = "A generalized merkle mountain range implementation"