diff --git a/Cargo.toml b/Cargo.toml
index 0a16ebc..0b9f0f3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,7 +11,7 @@ repository = "https://github.com/rust-num/num-derive"
 version = "0.3.3"
 readme = "README.md"
 exclude = ["/bors.toml", "/ci/*", "/.github/*"]
-edition = "2018"
+edition = "2021"
 rust-version = "1.56.0"
 
 [dependencies]
@@ -28,13 +28,21 @@ name = "num_derive"
 proc-macro = true
 test = false
 
-# Most of the tests are left implicily detected, compiled for Rust 2018,
-# but let's try a few of them with the old 2015 edition too.
+# Most of the tests are left implicily detected, compiled for Rust 2021,
+# but let's try a few of them with the older editions too.
 
 [[test]]
 name = "newtype-2015"
 edition = "2015"
 
+[[test]]
+name = "newtype-2018"
+edition = "2018"
+
 [[test]]
 name = "trivial-2015"
 edition = "2015"
+
+[[test]]
+name = "trivial-2018"
+edition = "2018"
diff --git a/tests/newtype-2018.rs b/tests/newtype-2018.rs
new file mode 100644
index 0000000..814529e
--- /dev/null
+++ b/tests/newtype-2018.rs
@@ -0,0 +1,2 @@
+// Same source, just compiled for 2018 edition
+include!("newtype.rs");
diff --git a/tests/trivial-2018.rs b/tests/trivial-2018.rs
new file mode 100644
index 0000000..92b971b
--- /dev/null
+++ b/tests/trivial-2018.rs
@@ -0,0 +1,2 @@
+// Same source, just compiled for 2018 edition
+include!("trivial.rs");