diff --git a/sim/mcuboot-sys/Cargo.toml b/sim/mcuboot-sys/Cargo.toml
index 1f6b81c..6d21bf5 100644
--- a/sim/mcuboot-sys/Cargo.toml
+++ b/sim/mcuboot-sys/Cargo.toml
@@ -5,7 +5,7 @@
 description = "A simple wrapper around the mcuboot code."
 build = "build.rs"
 publish = false
-edition = "2018"
+edition = "2021"
 
 [features]
 # By default, build with simplistic signature verification.