diff --git a/conformance/Cargo.toml b/conformance/Cargo.toml
index 570d92179..0ab6a4c6e 100644
--- a/conformance/Cargo.toml
+++ b/conformance/Cargo.toml
@@ -6,7 +6,7 @@ authors = [
   "Tokio Contributors <team@tokio.rs>",
 ]
 publish = false
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 bytes = "1"
diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
index eebda45d2..03a7ebcfb 100644
--- a/fuzz/Cargo.toml
+++ b/fuzz/Cargo.toml
@@ -6,7 +6,7 @@ authors = [
   "Tokio Contributors <team@tokio.rs>",
 ]
 publish = false
-edition = "2018"
+edition = "2021"
 
 [package.metadata]
 cargo-fuzz = true
diff --git a/fuzz/afl/proto3/Cargo.toml b/fuzz/afl/proto3/Cargo.toml
index d1e00d5df..b5aabdffa 100644
--- a/fuzz/afl/proto3/Cargo.toml
+++ b/fuzz/afl/proto3/Cargo.toml
@@ -2,7 +2,7 @@
 name = "fuzz-target-proto3"
 version = "0.1.0"
 authors = ["Prost developers"]
-edition = "2018"
+edition = "2021"
 
 [[bin]]
 name = "fuzz-target"
diff --git a/protobuf/Cargo.toml b/protobuf/Cargo.toml
index 3ae910202..7417f0ccc 100644
--- a/protobuf/Cargo.toml
+++ b/protobuf/Cargo.toml
@@ -6,7 +6,7 @@ authors = [
   "Tokio Contributors <team@tokio.rs>",
 ]
 publish = false
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 prost = { path = "../prost" }
diff --git a/tests-2018/Cargo.toml b/tests-2018/Cargo.toml
new file mode 100644
index 000000000..e4c87997f
--- /dev/null
+++ b/tests-2018/Cargo.toml
@@ -0,0 +1,38 @@
+[package]
+name = "tests-2018"
+version = "0.0.0"
+authors = [
+    "Dan Burkert <dan@danburkert.com>",
+    "Tokio Contributors <team@tokio.rs>",
+]
+publish = false
+edition = "2018"
+
+build = "../tests/src/build.rs"
+
+[lib]
+doctest = false
+path = "../tests/src/lib.rs"
+
+[features]
+default = ["std"]
+std = []
+
+[dependencies]
+anyhow = "1.0.1"
+bytes = "1"
+cfg-if = "1"
+prost = { path = "../prost" }
+prost-types = { path = "../prost-types" }
+protobuf = { path = "../protobuf" }
+
+[dev-dependencies]
+diff = "0.1"
+prost-build = { path = "../prost-build", features = ["cleanup-markdown"] }
+tempfile = "3"
+
+[build-dependencies]
+cfg-if = "1"
+env_logger = { version = "0.10", default-features = false }
+prost-build = { path = "../prost-build" }
+protobuf = { path = "../protobuf" }
diff --git a/tests-no-std/Cargo.toml b/tests-no-std/Cargo.toml
index 946bab5c6..70ae96612 100644
--- a/tests-no-std/Cargo.toml
+++ b/tests-no-std/Cargo.toml
@@ -6,7 +6,7 @@ authors = [
   "Tokio Contributors <team@tokio.rs>",
 ]
 publish = false
-edition = "2018"
+edition = "2021"
 
 build = "../tests/src/build.rs"
 
diff --git a/tests/Cargo.toml b/tests/Cargo.toml
index 46820582d..0dd709881 100644
--- a/tests/Cargo.toml
+++ b/tests/Cargo.toml
@@ -6,7 +6,7 @@ authors = [
   "Tokio Contributors <team@tokio.rs>",
 ]
 publish = false
-edition = "2018"
+edition = "2021"
 
 build = "src/build.rs"
 
diff --git a/tests/single-include/Cargo.toml b/tests/single-include/Cargo.toml
index 63a9b86cb..54408a0f1 100644
--- a/tests/single-include/Cargo.toml
+++ b/tests/single-include/Cargo.toml
@@ -2,7 +2,7 @@
 name = "single_include"
 version = "0.1.0"
 authors = ["Cameron Dart <cdart2@illinois.edu>"]
-edition = "2018"
+edition = "2021"
 publish = false
 license = "MIT"