diff --git a/README.md b/README.md
index e62820e7..eda660c2 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,7 @@ You may be looking for:
 <details>
 <summary>
 Click to show Cargo.toml.
-<a href="https://play.rust-lang.org/?edition=2018&gist=72755f28f99afc95e01d63174b28c1f5" target="_blank">Run this code in the playground.</a>
+<a href="https://play.rust-lang.org/?edition=2021&gist=72755f28f99afc95e01d63174b28c1f5" target="_blank">Run this code in the playground.</a>
 </summary>
 
 ```toml
diff --git a/test_suite/Cargo.toml b/test_suite/Cargo.toml
index 4076e735..4b5df83a 100644
--- a/test_suite/Cargo.toml
+++ b/test_suite/Cargo.toml
@@ -2,7 +2,7 @@
 name = "serde_test_suite"
 version = "0.0.0"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [features]
diff --git a/test_suite/no_std/Cargo.toml b/test_suite/no_std/Cargo.toml
index 9c8f6aa5..7909a2d6 100644
--- a/test_suite/no_std/Cargo.toml
+++ b/test_suite/no_std/Cargo.toml
@@ -2,7 +2,7 @@
 name = "serde_derive_tests_no_std"
 version = "0.0.0"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [dependencies]