diff --git a/quickjs.c b/quickjs.c
index 4c4d273..58c638a 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -7336,6 +7336,12 @@ static int JS_AddBrand(JSContext *ctx, JSValueConst obj, JSValueConst home_obj)
         return -1;
     }
     p1 = JS_VALUE_GET_OBJ(obj);
+    prs = find_own_property(&pr, p1, brand_atom);
+    if (unlikely(prs)) {
+        JS_FreeAtom(ctx, brand_atom);
+        JS_ThrowTypeError(ctx, "private method is already present");
+        return -1;
+    }
     pr = add_property(ctx, p1, brand_atom, JS_PROP_C_W_E);
     JS_FreeAtom(ctx, brand_atom);
     if (!pr)
diff --git a/test262_errors.txt b/test262_errors.txt
index e9462dd..e4f6c8b 100644
--- a/test262_errors.txt
+++ b/test262_errors.txt
@@ -29,13 +29,5 @@ test262/test/language/statements/async-generator/yield-star-promise-not-unwrappe
 test262/test/language/statements/async-generator/yield-star-promise-not-unwrapped.js:25: strict mode: TypeError: $DONE() not called
 test262/test/language/statements/async-generator/yield-star-return-then-getter-ticks.js:131: TypeError: $DONE() not called
 test262/test/language/statements/async-generator/yield-star-return-then-getter-ticks.js:131: strict mode: TypeError: $DONE() not called
-test262/test/language/statements/class/elements/private-method-double-initialisation-get-and-set.js:33: Test262Error: Expected a TypeError to be thrown but no exception was thrown at all
-test262/test/language/statements/class/elements/private-method-double-initialisation-get-and-set.js:33: strict mode: Test262Error: Expected a TypeError to be thrown but no exception was thrown at all
-test262/test/language/statements/class/elements/private-method-double-initialisation-get.js:32: Test262Error: Expected a TypeError to be thrown but no exception was thrown at all
-test262/test/language/statements/class/elements/private-method-double-initialisation-get.js:32: strict mode: Test262Error: Expected a TypeError to be thrown but no exception was thrown at all
-test262/test/language/statements/class/elements/private-method-double-initialisation-set.js:32: Test262Error: Expected a TypeError to be thrown but no exception was thrown at all
-test262/test/language/statements/class/elements/private-method-double-initialisation-set.js:32: strict mode: Test262Error: Expected a TypeError to be thrown but no exception was thrown at all
-test262/test/language/statements/class/elements/private-method-double-initialisation.js:32: Test262Error: Expected a TypeError to be thrown but no exception was thrown at all
-test262/test/language/statements/class/elements/private-method-double-initialisation.js:32: strict mode: Test262Error: Expected a TypeError to be thrown but no exception was thrown at all
 test262/test/language/statements/for-of/head-lhs-async-invalid.js:14: unexpected error type: Test262: This statement should not be evaluated.
 test262/test/language/statements/for-of/head-lhs-async-invalid.js:14: strict mode: unexpected error type: Test262: This statement should not be evaluated.