diff --git a/Cargo.toml b/Cargo.toml
index 6fed317..6c06c47 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,7 +2,7 @@
 name = "nuts-rs"
 version = "0.4.1"
 authors = ["Adrian Seyboldt <adrian.seyboldt@gmail.com>"]
-edition = "2023"
+edition = "2021"
 license = "MIT"
 repository = "https://github.com/pymc-devs/nuts-rs"
 keywords = ["statistics", "bayes"]