diff --git a/Cargo.toml b/Cargo.toml
index 50304b7..91d7b62 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-edition = "2018"
+edition = "2021"
 name = "cstree"
 version = "0.9.0"
 authors = [