diff --git a/ecmascript/transforms/compat/src/es2015/regenerator/hoist.rs b/ecmascript/transforms/compat/src/es2015/regenerator/hoist.rs
index 4bceb4e90a5..e576a62335e 100644
--- a/ecmascript/transforms/compat/src/es2015/regenerator/hoist.rs
+++ b/ecmascript/transforms/compat/src/es2015/regenerator/hoist.rs
@@ -5,7 +5,7 @@ use swc_ecma_ast::*;
 use swc_ecma_utils::{find_ids, private_ident};
 use swc_ecma_visit::{noop_fold_type, Fold, FoldWith};
 
-pub(super) type Vars = SmallVec<[Ident; 32]>;
+pub(super) type Vars = SmallVec<[Ident; 12]>;
 
 pub(super) fn hoist<T>(node: T) -> (T, Hoister)
 where
@@ -138,7 +138,10 @@ impl Fold for Hoister {
 
             VarDeclOrPat::VarDecl(mut var) => {
                 if var.decls.len() == 1 && var.decls[0].init.is_none() {
-                    return var.decls.remove(0).name.into();
+                    let pat = var.decls.remove(0).name;
+                    self.vars.extend(find_ids(&pat));
+
+                    return pat.into();
                 }
 
                 var.into()
@@ -154,4 +157,20 @@ impl Fold for Hoister {
             _ => var.fold_children_with(self),
         }
     }
+
+    fn fold_opt_var_decl_or_expr(&mut self, v: Option<VarDeclOrExpr>) -> Option<VarDeclOrExpr> {
+        let v = v.fold_children_with(self);
+
+        match &v {
+            Some(VarDeclOrExpr::Expr(e)) => {
+                if e.is_invalid() {
+                    return None;
+                }
+            }
+
+            _ => {}
+        }
+
+        v
+    }
 }
diff --git a/ecmascript/transforms/compat/src/es2015/regenerator/mod.rs b/ecmascript/transforms/compat/src/es2015/regenerator/mod.rs
index c016cd3dc51..c6be29a0485 100644
--- a/ecmascript/transforms/compat/src/es2015/regenerator/mod.rs
+++ b/ecmascript/transforms/compat/src/es2015/regenerator/mod.rs
@@ -16,7 +16,6 @@ pub fn regenerator(global_mark: Mark) -> impl Fold {
     Regenerator {
         global_mark,
         regenerator_runtime: Default::default(),
-        outer_fn_vars: Default::default(),
         top_level_vars: Default::default(),
     }
 }
@@ -26,8 +25,6 @@ struct Regenerator {
     global_mark: Mark,
     /// [Some] if used.
     regenerator_runtime: Option<Ident>,
-    /// Variables declared in outer function.
-    outer_fn_vars: Vec<VarDeclarator>,
     /// mark
     top_level_vars: Vec<VarDeclarator>,
 }
@@ -322,28 +319,27 @@ impl Regenerator {
         f.body = f.body.fold_with(&mut FnSentVisitor { ctx: ctx.clone() });
         let uses_this = contains_this_expr(&f.body);
         let (body, hoister) = hoist(f.body.unwrap());
-        self.outer_fn_vars
-            .extend(hoister.vars.into_iter().map(|id| VarDeclarator {
+        let mut outer_fn_vars = vec![];
+        outer_fn_vars.extend(hoister.vars.into_iter().map(|id| VarDeclarator {
+            span: DUMMY_SP,
+            name: Pat::Ident(id.into()),
+            init: None,
+            definite: false,
+        }));
+        outer_fn_vars.extend(hoister.arguments.into_iter().map(|id| {
+            VarDeclarator {
                 span: DUMMY_SP,
-                name: Pat::Ident(id.into()),
-                init: None,
+                name: Pat::Ident(id.clone().into()),
+                init: Some(Box::new(
+                    Ident {
+                        sym: js_word!("arguments"),
+                        ..id
+                    }
+                    .into(),
+                )),
                 definite: false,
-            }));
-        self.outer_fn_vars
-            .extend(hoister.arguments.into_iter().map(|id| {
-                VarDeclarator {
-                    span: DUMMY_SP,
-                    name: Pat::Ident(id.clone().into()),
-                    init: Some(Box::new(
-                        Ident {
-                            sym: js_word!("arguments"),
-                            ..id
-                        }
-                        .into(),
-                    )),
-                    definite: false,
-                }
-            }));
+            }
+        }));
 
         handler.explode_stmts(body.stmts);
 
@@ -419,11 +415,11 @@ impl Regenerator {
                     span: body_span,
                     stmts: {
                         let mut buf = vec![];
-                        if !self.outer_fn_vars.is_empty() {
+                        if !outer_fn_vars.is_empty() {
                             buf.push(Stmt::Decl(Decl::Var(VarDecl {
                                 span: DUMMY_SP,
                                 kind: VarDeclKind::Var,
-                                decls: take(&mut self.outer_fn_vars),
+                                decls: outer_fn_vars,
                                 declare: false,
                             })));
                         }
diff --git a/ecmascript/transforms/compat/tests/es2015_classes.rs b/ecmascript/transforms/compat/tests/es2015_classes.rs
index 5a1818bfa1a..4913b9d3946 100644
--- a/ecmascript/transforms/compat/tests/es2015_classes.rs
+++ b/ecmascript/transforms/compat/tests/es2015_classes.rs
@@ -1,3 +1,5 @@
+use std::{fs::read_to_string, path::PathBuf};
+
 use swc_common::{chain, Mark};
 use swc_ecma_parser::Syntax;
 use swc_ecma_transforms_base::resolver::resolver;
@@ -7,7 +9,7 @@ use swc_ecma_transforms_compat::{
     es2016, es2017, es2018, es2020,
     es2020::class_properties,
 };
-use swc_ecma_transforms_testing::{test, test_exec, Tester};
+use swc_ecma_transforms_testing::{compare_stdout, test, test_exec, Tester};
 use swc_ecma_visit::Fold;
 
 fn syntax() -> Syntax {
@@ -6531,3 +6533,13 @@ var Extended = function(Base) {
 }(Base);
     "
 );
+
+#[testing::fixture("tests/fixture/classes/**/exec.js")]
+fn exec(input: PathBuf) {
+    let src = read_to_string(&input).unwrap();
+    compare_stdout(
+        Default::default(),
+        |t| classes(Some(t.comments.clone())),
+        &src,
+    );
+}
diff --git a/ecmascript/transforms/compat/tests/fixture/classes/case1/exec.js b/ecmascript/transforms/compat/tests/fixture/classes/case1/exec.js
new file mode 100644
index 00000000000..6938d62e8b1
--- /dev/null
+++ b/ecmascript/transforms/compat/tests/fixture/classes/case1/exec.js
@@ -0,0 +1,17 @@
+const sleep = (ms) => new Promise((resolve, reject) => { setTimeout(() => resolve(), ms) })
+
+class Project {
+    constructor(name) {
+        this.name = name
+    }
+};
+
+Project.f = async function () {
+    await sleep(100)
+    console.log(this['a'])
+    return new this('a')
+}
+
+Project.f().then((project) => {
+    console.log(project.name)
+})
\ No newline at end of file
diff --git a/ecmascript/transforms/compat/tests/fixture/classes/case2/exec.js b/ecmascript/transforms/compat/tests/fixture/classes/case2/exec.js
new file mode 100644
index 00000000000..992398ce4bd
--- /dev/null
+++ b/ecmascript/transforms/compat/tests/fixture/classes/case2/exec.js
@@ -0,0 +1,16 @@
+const sleep = (ms) => new Promise((resolve, reject) => { setTimeout(() => resolve(), ms) })
+
+class Project {
+    constructor(name) {
+        this.name = name
+    }
+    static async g() {
+        await sleep(100)
+        console.log(this['a'])
+        return new this('a')
+    }
+};
+
+Project.g().then((project) => {
+    console.log(project.name)
+})
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es2015/input/.swcrc b/tests/fixture/issue-2164/es2015/input/.swcrc
new file mode 100644
index 00000000000..99a58761f54
--- /dev/null
+++ b/tests/fixture/issue-2164/es2015/input/.swcrc
@@ -0,0 +1,5 @@
+{
+    "jsc": {
+        "target": "es2015"
+    }
+}
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es2015/input/index.js b/tests/fixture/issue-2164/es2015/input/index.js
new file mode 100644
index 00000000000..3cbe24c56fa
--- /dev/null
+++ b/tests/fixture/issue-2164/es2015/input/index.js
@@ -0,0 +1,3 @@
+async function fn() {
+    for (const key in {});
+}
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es2015/output/index.js b/tests/fixture/issue-2164/es2015/output/index.js
new file mode 100644
index 00000000000..d979091920a
--- /dev/null
+++ b/tests/fixture/issue-2164/es2015/output/index.js
@@ -0,0 +1,49 @@
+import regeneratorRuntime from "regenerator-runtime";
+function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) {
+    try {
+        var info = gen[key](arg);
+        var value = info.value;
+    } catch (error) {
+        reject(error);
+        return;
+    }
+    if (info.done) {
+        resolve(value);
+    } else {
+        Promise.resolve(value).then(_next, _throw);
+    }
+}
+function _asyncToGenerator(fn) {
+    return function() {
+        var self = this, args = arguments;
+        return new Promise(function(resolve, reject) {
+            var gen = fn.apply(self, args);
+            function _next(value) {
+                asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value);
+            }
+            function _throw(err) {
+                asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err);
+            }
+            _next(undefined);
+        });
+    };
+}
+function _fn() {
+    _fn = _asyncToGenerator(regeneratorRuntime.mark(function _callee() {
+        var key;
+        return regeneratorRuntime.wrap(function _callee$(_ctx) {
+            while(1)switch(_ctx.prev = _ctx.next){
+                case 0:
+                    for(key in {
+                    });
+                case 1:
+                case "end":
+                    return _ctx.stop();
+            }
+        }, _callee);
+    }));
+    return _fn.apply(this, arguments);
+}
+function fn() {
+    return _fn.apply(this, arguments);
+}
diff --git a/tests/fixture/issue-2164/es2016/input/.swcrc b/tests/fixture/issue-2164/es2016/input/.swcrc
new file mode 100644
index 00000000000..1d664422ac4
--- /dev/null
+++ b/tests/fixture/issue-2164/es2016/input/.swcrc
@@ -0,0 +1,5 @@
+{
+    "jsc": {
+        "target": "es2016"
+    }
+}
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es2016/input/index.js b/tests/fixture/issue-2164/es2016/input/index.js
new file mode 100644
index 00000000000..3cbe24c56fa
--- /dev/null
+++ b/tests/fixture/issue-2164/es2016/input/index.js
@@ -0,0 +1,3 @@
+async function fn() {
+    for (const key in {});
+}
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es2016/output/index.js b/tests/fixture/issue-2164/es2016/output/index.js
new file mode 100644
index 00000000000..f621aac5ead
--- /dev/null
+++ b/tests/fixture/issue-2164/es2016/output/index.js
@@ -0,0 +1,39 @@
+function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) {
+    try {
+        var info = gen[key](arg);
+        var value = info.value;
+    } catch (error) {
+        reject(error);
+        return;
+    }
+    if (info.done) {
+        resolve(value);
+    } else {
+        Promise.resolve(value).then(_next, _throw);
+    }
+}
+function _asyncToGenerator(fn) {
+    return function() {
+        var self = this, args = arguments;
+        return new Promise(function(resolve, reject) {
+            var gen = fn.apply(self, args);
+            function _next(value) {
+                asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value);
+            }
+            function _throw(err) {
+                asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err);
+            }
+            _next(undefined);
+        });
+    };
+}
+function _fn() {
+    _fn = _asyncToGenerator(function*() {
+        for(const key in {
+        });
+    });
+    return _fn.apply(this, arguments);
+}
+function fn() {
+    return _fn.apply(this, arguments);
+}
diff --git a/tests/fixture/issue-2164/es2018/input/.swcrc b/tests/fixture/issue-2164/es2018/input/.swcrc
new file mode 100644
index 00000000000..f53b49e5134
--- /dev/null
+++ b/tests/fixture/issue-2164/es2018/input/.swcrc
@@ -0,0 +1,5 @@
+{
+    "jsc": {
+        "target": "es2018"
+    }
+}
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es2018/input/index.js b/tests/fixture/issue-2164/es2018/input/index.js
new file mode 100644
index 00000000000..3cbe24c56fa
--- /dev/null
+++ b/tests/fixture/issue-2164/es2018/input/index.js
@@ -0,0 +1,3 @@
+async function fn() {
+    for (const key in {});
+}
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es2018/output/index.js b/tests/fixture/issue-2164/es2018/output/index.js
new file mode 100644
index 00000000000..293d0f68ed4
--- /dev/null
+++ b/tests/fixture/issue-2164/es2018/output/index.js
@@ -0,0 +1,4 @@
+async function fn() {
+    for(const key in {
+    });
+}
diff --git a/tests/fixture/issue-2164/es5/input/.swcrc b/tests/fixture/issue-2164/es5/input/.swcrc
new file mode 100644
index 00000000000..088bc6e5217
--- /dev/null
+++ b/tests/fixture/issue-2164/es5/input/.swcrc
@@ -0,0 +1,5 @@
+{
+    "jsc": {
+        "target": "es5"
+    }
+}
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es5/input/index.js b/tests/fixture/issue-2164/es5/input/index.js
new file mode 100644
index 00000000000..3cbe24c56fa
--- /dev/null
+++ b/tests/fixture/issue-2164/es5/input/index.js
@@ -0,0 +1,3 @@
+async function fn() {
+    for (const key in {});
+}
\ No newline at end of file
diff --git a/tests/fixture/issue-2164/es5/output/index.js b/tests/fixture/issue-2164/es5/output/index.js
new file mode 100644
index 00000000000..d979091920a
--- /dev/null
+++ b/tests/fixture/issue-2164/es5/output/index.js
@@ -0,0 +1,49 @@
+import regeneratorRuntime from "regenerator-runtime";
+function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) {
+    try {
+        var info = gen[key](arg);
+        var value = info.value;
+    } catch (error) {
+        reject(error);
+        return;
+    }
+    if (info.done) {
+        resolve(value);
+    } else {
+        Promise.resolve(value).then(_next, _throw);
+    }
+}
+function _asyncToGenerator(fn) {
+    return function() {
+        var self = this, args = arguments;
+        return new Promise(function(resolve, reject) {
+            var gen = fn.apply(self, args);
+            function _next(value) {
+                asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value);
+            }
+            function _throw(err) {
+                asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err);
+            }
+            _next(undefined);
+        });
+    };
+}
+function _fn() {
+    _fn = _asyncToGenerator(regeneratorRuntime.mark(function _callee() {
+        var key;
+        return regeneratorRuntime.wrap(function _callee$(_ctx) {
+            while(1)switch(_ctx.prev = _ctx.next){
+                case 0:
+                    for(key in {
+                    });
+                case 1:
+                case "end":
+                    return _ctx.stop();
+            }
+        }, _callee);
+    }));
+    return _fn.apply(this, arguments);
+}
+function fn() {
+    return _fn.apply(this, arguments);
+}