diff --git a/quickjs.c b/quickjs.c
index da725538..ac267078 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -40055,7 +40055,67 @@ static JSValue js_iterator_proto_map(JSContext *ctx, JSValue this_val,
 static JSValue js_iterator_proto_reduce(JSContext *ctx, JSValue this_val,
                                         int argc, JSValue *argv)
 {
-    return JS_ThrowInternalError(ctx, "TODO implement Iterator.prototype.reduce");
+    JSValue item, method, ret, func, index_val, acc;
+    JSValue args[3];
+    int64_t idx;
+    BOOL done;
+
+    if (!JS_IsObject(this_val))
+        return JS_ThrowTypeError(ctx, "Iterator.prototype.reduce called on non-object");
+    if (check_function(ctx, argv[0]))
+        return JS_EXCEPTION;
+    acc = JS_UNDEFINED;
+    func = js_dup(argv[0]);
+    method = JS_GetProperty(ctx, this_val, JS_ATOM_next);
+    if (JS_IsException(method))
+        goto exception;
+    if (argc > 1) {
+        acc = js_dup(argv[1]);
+        idx = 0;
+    } else {
+        acc = JS_IteratorNext(ctx, this_val, method, 0, NULL, &done);
+        if (JS_IsException(acc))
+            goto exception;
+        if (done) {
+            JS_ThrowTypeError(ctx, "empty iterator");
+            goto exception;
+        }
+        idx = 1;
+    }
+    for (/* empty */; /*empty*/; idx++) {
+        item = JS_IteratorNext(ctx, this_val, method, 0, NULL, &done);
+        if (JS_IsException(item))
+            goto exception;
+        if (done)
+            break;
+        index_val = JS_NewInt64(ctx, idx);
+        if (JS_IsException(index_val)) {
+            JS_FreeValue(ctx, item);
+            goto exception;
+        }
+        args[0] = acc;
+        args[1] = item;
+        args[2] = index_val;
+        ret = JS_Call(ctx, func, JS_UNDEFINED, countof(args), args);
+        JS_FreeValue(ctx, item);
+        JS_FreeValue(ctx, index_val);
+        if (JS_IsException(ret))
+            goto exception;
+        JS_FreeValue(ctx, acc);
+        acc = ret;
+        index_val = JS_UNDEFINED;
+        ret = JS_UNDEFINED;
+        item = JS_UNDEFINED;
+    }
+    JS_FreeValue(ctx, func);
+    JS_FreeValue(ctx, method);
+    return acc;
+exception:
+    JS_IteratorClose(ctx, this_val, TRUE);
+    JS_FreeValue(ctx, acc);
+    JS_FreeValue(ctx, func);
+    JS_FreeValue(ctx, method);
+    return JS_EXCEPTION;
 }
 
 static JSValue js_iterator_proto_some(JSContext *ctx, JSValue this_val,
diff --git a/test262_errors.txt b/test262_errors.txt
index d608e0b5..4dc21144 100644
--- a/test262_errors.txt
+++ b/test262_errors.txt
@@ -320,52 +320,6 @@ test262/test/built-ins/Iterator/prototype/map/underlying-iterator-closed-in-para
 test262/test/built-ins/Iterator/prototype/map/underlying-iterator-closed-in-parallel.js:19: strict mode: InternalError: TODO implement Iterator.prototype.map
 test262/test/built-ins/Iterator/prototype/map/underlying-iterator-closed.js:21: InternalError: TODO implement Iterator.prototype.map
 test262/test/built-ins/Iterator/prototype/map/underlying-iterator-closed.js:21: strict mode: InternalError: TODO implement Iterator.prototype.map
-test262/test/built-ins/Iterator/prototype/reduce/argument-effect-order.js:16: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/argument-effect-order.js:16: strict mode: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/callable.js:10: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/callable.js:10: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/get-next-method-only-once.js:33: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/get-next-method-only-once.js:33: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/get-next-method-throws.js:15: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/get-next-method-throws.js:15: strict mode: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/iterator-already-exhausted-initial-value.js:20: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/iterator-already-exhausted-initial-value.js:20: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/iterator-already-exhausted-no-initial-value.js:19: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/iterator-already-exhausted-no-initial-value.js:19: strict mode: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/iterator-yields-once-initial-value.js:32: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/iterator-yields-once-initial-value.js:32: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/iterator-yields-once-no-initial-value.js:23: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/iterator-yields-once-no-initial-value.js:23: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/next-method-returns-non-object.js:21: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/next-method-returns-non-object.js:21: strict mode: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/next-method-returns-throwing-done.js:17: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/next-method-returns-throwing-done.js:17: strict mode: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/next-method-returns-throwing-value-done.js:28: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/next-method-returns-throwing-value-done.js:28: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/next-method-returns-throwing-value.js:18: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/next-method-returns-throwing-value.js:18: strict mode: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/next-method-throws.js:15: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/next-method-throws.js:15: strict mode: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/non-callable-reducer.js:18: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/non-callable-reducer.js:18: strict mode: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/reducer-args-initial-value.js:42: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/reducer-args-initial-value.js:42: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/reducer-args-no-initial-value.js:38: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/reducer-args-no-initial-value.js:38: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/reducer-memo-can-be-any-type.js:28: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/reducer-memo-can-be-any-type.js:28: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/reducer-this.js:29: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/reducer-this.js:29: strict mode: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/reducer-throws-then-closing-iterator-also-throws.js:30: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/reducer-throws-then-closing-iterator-also-throws.js:30: strict mode: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/reducer-throws.js:32: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/reducer-throws.js:32: strict mode: Test262Error: Expected a Test262Error but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/this-non-callable-next.js:13: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/this-non-callable-next.js:13: strict mode: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/this-non-object.js:23: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/this-non-object.js:23: strict mode: Test262Error: Expected a TypeError but got a InternalError
-test262/test/built-ins/Iterator/prototype/reduce/this-plain-iterator.js:29: InternalError: TODO implement Iterator.prototype.reduce
-test262/test/built-ins/Iterator/prototype/reduce/this-plain-iterator.js:29: strict mode: InternalError: TODO implement Iterator.prototype.reduce
 test262/test/built-ins/Iterator/prototype/some/argument-effect-order.js:16: Test262Error: Expected a TypeError but got a InternalError
 test262/test/built-ins/Iterator/prototype/some/argument-effect-order.js:16: strict mode: Test262Error: Expected a TypeError but got a InternalError
 test262/test/built-ins/Iterator/prototype/some/callable.js:10: InternalError: TODO implement Iterator.prototype.some