diff --git a/src/closures.rs b/src/closures.rs
index 8a4089a56f0..23cd6e4c092 100644
--- a/src/closures.rs
+++ b/src/closures.rs
@@ -29,7 +29,7 @@ pub(crate) fn rewrite_closure(
     binder: &ast::ClosureBinder,
     constness: ast::Const,
     capture: ast::CaptureBy,
-    is_async: &ast::Async,
+    coro_kind: &ast::CoroutineKind,
     movability: ast::Movability,
     fn_decl: &ast::FnDecl,
     body: &ast::Expr,
@@ -40,7 +40,7 @@ pub(crate) fn rewrite_closure(
     debug!("rewrite_closure {:?}", body);
 
     let (prefix, extra_offset) = rewrite_closure_fn_decl(
-        binder, constness, capture, is_async, movability, fn_decl, body, span, context, shape,
+        binder, constness, capture, coro_kind, movability, fn_decl, body, span, context, shape,
     )?;
     // 1 = space between `|...|` and body.
     let body_shape = shape.offset_left(extra_offset)?;
@@ -233,7 +233,7 @@ fn rewrite_closure_fn_decl(
     binder: &ast::ClosureBinder,
     constness: ast::Const,
     capture: ast::CaptureBy,
-    asyncness: &ast::Async,
+    coro_kind: &ast::CoroutineKind,
     movability: ast::Movability,
     fn_decl: &ast::FnDecl,
     body: &ast::Expr,
@@ -263,7 +263,8 @@ fn rewrite_closure_fn_decl(
     } else {
         ""
     };
-    let is_async = if asyncness.is_async() { "async " } else { "" };
+    let is_async = if coro_kind.is_async() { "async " } else { "" };
+    let is_gen = if coro_kind.is_gen() { "gen " } else { "" };
     let mover = if matches!(capture, ast::CaptureBy::Value { .. }) {
         "move "
     } else {
@@ -272,7 +273,14 @@ fn rewrite_closure_fn_decl(
     // 4 = "|| {".len(), which is overconservative when the closure consists of
     // a single expression.
     let nested_shape = shape
-        .shrink_left(binder.len() + const_.len() + immovable.len() + is_async.len() + mover.len())?
+        .shrink_left(
+            binder.len()
+                + const_.len()
+                + immovable.len()
+                + is_async.len()
+                + is_gen.len()
+                + mover.len(),
+        )?
         .sub_width(4)?;
 
     // 1 = |
@@ -310,7 +318,7 @@ fn rewrite_closure_fn_decl(
         .tactic(tactic)
         .preserve_newline(true);
     let list_str = write_list(&item_vec, &fmt)?;
-    let mut prefix = format!("{binder}{const_}{immovable}{is_async}{mover}|{list_str}|");
+    let mut prefix = format!("{binder}{const_}{immovable}{is_async}{is_gen}{mover}|{list_str}|");
 
     if !ret_str.is_empty() {
         if prefix.contains('\n') {
@@ -339,7 +347,7 @@ pub(crate) fn rewrite_last_closure(
             ref binder,
             constness,
             capture_clause,
-            ref asyncness,
+            ref coro_kind,
             movability,
             ref fn_decl,
             ref body,
@@ -360,7 +368,7 @@ pub(crate) fn rewrite_last_closure(
             binder,
             constness,
             capture_clause,
-            asyncness,
+            coro_kind,
             movability,
             fn_decl,
             body,
diff --git a/src/expr.rs b/src/expr.rs
index 60e0e007b1d..4515c27be37 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -212,7 +212,7 @@ pub(crate) fn format_expr(
             &cl.binder,
             cl.constness,
             cl.capture_clause,
-            &cl.asyncness,
+            &cl.coro_kind,
             cl.movability,
             &cl.fn_decl,
             &cl.body,
diff --git a/src/items.rs b/src/items.rs
index edb5a5b629a..0a1f823fe87 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -287,7 +287,7 @@ pub(crate) struct FnSig<'a> {
     decl: &'a ast::FnDecl,
     generics: &'a ast::Generics,
     ext: ast::Extern,
-    is_async: Cow<'a, ast::Async>,
+    coro_kind: Cow<'a, ast::CoroutineKind>,
     constness: ast::Const,
     defaultness: ast::Defaultness,
     unsafety: ast::Unsafe,
@@ -302,7 +302,7 @@ pub(crate) fn from_method_sig(
     ) -> FnSig<'a> {
         FnSig {
             unsafety: method_sig.header.unsafety,
-            is_async: Cow::Borrowed(&method_sig.header.asyncness),
+            coro_kind: Cow::Borrowed(&method_sig.header.coro_kind),
             constness: method_sig.header.constness,
             defaultness: ast::Defaultness::Final,
             ext: method_sig.header.ext,
@@ -328,7 +328,7 @@ pub(crate) fn from_fn_kind(
                 generics,
                 ext: fn_sig.header.ext,
                 constness: fn_sig.header.constness,
-                is_async: Cow::Borrowed(&fn_sig.header.asyncness),
+                coro_kind: Cow::Borrowed(&fn_sig.header.coro_kind),
                 defaultness,
                 unsafety: fn_sig.header.unsafety,
                 visibility: vis,
@@ -343,7 +343,7 @@ fn to_str(&self, context: &RewriteContext<'_>) -> String {
         result.push_str(&*format_visibility(context, self.visibility));
         result.push_str(format_defaultness(self.defaultness));
         result.push_str(format_constness(self.constness));
-        result.push_str(format_async(&self.is_async));
+        result.push_str(format_coro(&self.coro_kind));
         result.push_str(format_unsafety(self.unsafety));
         result.push_str(&format_extern(
             self.ext,
diff --git a/src/utils.rs b/src/utils.rs
index fd49030bf1b..18d8f0cdbd7 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -75,10 +75,11 @@ pub(crate) fn format_visibility(
 }
 
 #[inline]
-pub(crate) fn format_async(is_async: &ast::Async) -> &'static str {
-    match is_async {
-        ast::Async::Yes { .. } => "async ",
-        ast::Async::No => "",
+pub(crate) fn format_coro(coro_kind: &ast::CoroutineKind) -> &'static str {
+    match coro_kind {
+        ast::CoroutineKind::Async { .. } => "async ",
+        ast::CoroutineKind::Gen { .. } => "gen ",
+        ast::CoroutineKind::None => "",
     }
 }