diff --git a/rustfmt.toml b/rustfmt.toml
index 797eccdad99..f1241e74b0a 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -2,5 +2,5 @@ max_width = 120
 comment_width = 100
 match_block_trailing_comma = true
 wrap_comments = true
-
+edition = "2018"
 error_on_line_overflow = true
diff --git a/tests/ui/issue_4266.rs b/tests/ui/issue_4266.rs
index 737e718c4c0..953879f7bed 100644
--- a/tests/ui/issue_4266.rs
+++ b/tests/ui/issue_4266.rs
@@ -2,41 +2,37 @@
 #![feature(async_await)]
 #![allow(dead_code)]
 
-// No edition 2018
-#[rustfmt::skip]
-mod m {
-    async fn sink1<'a>(_: &'a str) {} // lint
-    async fn sink1_elided(_: &str) {} // ok
+async fn sink1<'a>(_: &'a str) {} // lint
+async fn sink1_elided(_: &str) {} // ok
 
-    // lint
-    async fn one_to_one<'a>(s: &'a str) -> &'a str {
-        s
-    }
+// lint
+async fn one_to_one<'a>(s: &'a str) -> &'a str {
+    s
+}
 
+// ok
+async fn one_to_one_elided(s: &str) -> &str {
+    s
+}
+
+// ok
+async fn all_to_one<'a>(a: &'a str, _b: &'a str) -> &'a str {
+    a
+}
+
+// async fn unrelated(_: &str, _: &str) {} // Not allowed in async fn
+
+// #3988
+struct Foo;
+impl Foo {
     // ok
-    async fn one_to_one_elided(s: &str) -> &str {
-        s
-    }
+    pub async fn foo(&mut self) {}
+}
 
-    // ok
-    async fn all_to_one<'a>(a: &'a str, _b: &'a str) -> &'a str {
-        a
-    }
-
-    // async fn unrelated(_: &str, _: &str) {} // Not allowed in async fn
-
-    // #3988
-    struct Foo;
-    impl Foo {
-        // ok
-        pub async fn foo(&mut self) {}
-    }
-
-    // rust-lang/rust#61115
-    // ok
-    async fn print(s: &str) {
-        println!("{}", s);
-    }
+// rust-lang/rust#61115
+// ok
+async fn print(s: &str) {
+    println!("{}", s);
 }
 
 fn main() {}
diff --git a/tests/ui/issue_4266.stderr b/tests/ui/issue_4266.stderr
index 649d01dca1e..8b4e70eb9c2 100644
--- a/tests/ui/issue_4266.stderr
+++ b/tests/ui/issue_4266.stderr
@@ -1,18 +1,18 @@
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/issue_4266.rs:8:5
+  --> $DIR/issue_4266.rs:5:1
    |
-LL |     async fn sink1<'a>(_: &'a str) {} // lint
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | async fn sink1<'a>(_: &'a str) {} // lint
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/issue_4266.rs:12:5
+  --> $DIR/issue_4266.rs:9:1
    |
-LL | /     async fn one_to_one<'a>(s: &'a str) -> &'a str {
-LL | |         s
-LL | |     }
-   | |_____^
+LL | / async fn one_to_one<'a>(s: &'a str) -> &'a str {
+LL | |     s
+LL | | }
+   | |_^
 
 error: aborting due to 2 previous errors