diff --git a/crates/swc/tests/fixture/issues-6xxx/6373/output/input.js b/crates/swc/tests/fixture/issues-6xxx/6373/output/input.js
index f719f64a4bba..e59f2a3523e7 100644
--- a/crates/swc/tests/fixture/issues-6xxx/6373/output/input.js
+++ b/crates/swc/tests/fixture/issues-6xxx/6373/output/input.js
@@ -1,10 +1,9 @@
 import _class_call_check from "@swc/helpers/src/_class_call_check.mjs";
-var _brand_check_y = new WeakSet(), _tmp;
 var x = function x() {
     "use strict";
     _class_call_check(this, x);
 };
 var _y = {
     writable: true,
-    value: (_tmp = _brand_check_y.has(x), _brand_check_y.add(x), _tmp)
+    value: x === x
 };
diff --git a/crates/swc/tests/tsc-references/privateNameInInExpressionUnused.1.normal.js b/crates/swc/tests/tsc-references/privateNameInInExpressionUnused.1.normal.js
index b070e32e71cf..54cebaf32e76 100644
--- a/crates/swc/tests/tsc-references/privateNameInInExpressionUnused.1.normal.js
+++ b/crates/swc/tests/tsc-references/privateNameInInExpressionUnused.1.normal.js
@@ -1,10 +1,9 @@
 //// [privateNameInInExpressionUnused.ts]
-var _brand_check_brand = new WeakSet();
 class Foo {
     #unused;
-    #brand = void _brand_check_brand.add(this);
+    #brand;
     isFoo(v) {
         // This should count as using/reading '#brand'
-        return _brand_check_brand.has(v);
+        return #brand in v;
     }
 }
diff --git a/crates/swc/tests/tsc-references/privateNameInInExpressionUnused.2.minified.js b/crates/swc/tests/tsc-references/privateNameInInExpressionUnused.2.minified.js
index 2cbd89df2d27..62c9d362c257 100644
--- a/crates/swc/tests/tsc-references/privateNameInInExpressionUnused.2.minified.js
+++ b/crates/swc/tests/tsc-references/privateNameInInExpressionUnused.2.minified.js
@@ -1,2 +1 @@
 //// [privateNameInInExpressionUnused.ts]
-new WeakSet();
diff --git a/crates/swc_ecma_parser/tests/test262-error-references/fail/c3731145e0e65d1d.js.stderr b/crates/swc_ecma_parser/tests/test262-error-references/fail/c3731145e0e65d1d.js.stderr
index 834ca3cda87b..03085de60270 100644
--- a/crates/swc_ecma_parser/tests/test262-error-references/fail/c3731145e0e65d1d.js.stderr
+++ b/crates/swc_ecma_parser/tests/test262-error-references/fail/c3731145e0e65d1d.js.stderr
@@ -1,7 +1,6 @@
 
-  x Unexpected token `#`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint, string, regexp, `
-  | for template literal, (, or an identifier
+  x Expected ident
    ,-[$DIR/tests/test262-parser/fail/c3731145e0e65d1d.js:1:1]
  1 | #=
-   : ^
+   :  ^
    `----