diff --git a/packages/hydrooj/package.json b/packages/hydrooj/package.json
index 3e8efd0e9..c650946b9 100644
--- a/packages/hydrooj/package.json
+++ b/packages/hydrooj/package.json
@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "2.17.3",
+    "version": "2.17.4",
     "bin": "bin/hydrooj.js",
     "main": "dist/loader.js",
     "typings": "dist/loader.d.ts",
diff --git a/packages/hydrooj/src/handler/problem.ts b/packages/hydrooj/src/handler/problem.ts
index 489fd4a99..43d5086b9 100644
--- a/packages/hydrooj/src/handler/problem.ts
+++ b/packages/hydrooj/src/handler/problem.ts
@@ -480,11 +480,8 @@ export class ProblemFilesHandler extends ProblemDetailHandler {
     @post('type', Types.Range(['testdata', 'additional_file']), true)
     async postDeleteFiles(domainId: string, files: string[], type = 'testdata') {
         if (this.pdoc.owner !== this.user._id) this.checkPerm(PERM.PERM_EDIT_PROBLEM);
-        if (type === 'testdata') {
-            await problem.delTestdata(domainId, this.pdoc.docId, files);
-        } else {
-            await storage.del(files.map((file) => `problem/${this.pdoc.domainId}/${this.pdoc.docId}/${type}/${file}`));
-        }
+        if (type === 'testdata') await problem.delTestdata(domainId, this.pdoc.docId, files);
+        else await problem.delAdditionalFile(domainId, this.pdoc.docId, files);
         this.back();
     }
 }
diff --git a/packages/hydrooj/src/model/document.ts b/packages/hydrooj/src/model/document.ts
index 79bee756b..0b4b20f06 100644
--- a/packages/hydrooj/src/model/document.ts
+++ b/packages/hydrooj/src/model/document.ts
@@ -200,13 +200,14 @@ export async function pull<K extends keyof DocType, T extends ArrayKeys<DocType[
     return res.value;
 }
 
-export async function deleteSub<K extends keyof DocType>(
-    domainId: string, docType: K, docId: DocType[K]['docId'],
-    key: ArrayKeys<DocType[K]>, subId: ObjectID,
-): Promise<DocType[K]> {
+export async function deleteSub<T extends keyof DocType, K extends ArrayKeys<DocType[T]>>(
+    domainId: string, docType: T, docId: DocType[T]['docId'],
+    key: K, subId: DocType[T][K][0]['_id'] | DocType[T][K][0]['_id'][],
+): Promise<DocType[T]> {
+    subId = (subId instanceof Array) ? subId : [subId];
     const res = await coll.findOneAndUpdate(
         { domainId, docType, docId },
-        { $pull: { [key]: { _id: subId } } },
+        { $pull: { [key]: { _id: { $in: subId } } } },
         { returnOriginal: false },
     );
     return res.value;
@@ -214,8 +215,8 @@ export async function deleteSub<K extends keyof DocType>(
 
 export async function getSub<T extends keyof DocType, K extends ArrayKeys<DocType[T]>>(
     domainId: string, docType: T, docId: DocType[T]['docId'],
-    key: K, subId: ObjectID,
-): Promise<[DocType[T], DocType[T][K]][0]> {
+    key: K, subId: DocType[T][K][0]['_id'],
+): Promise<[DocType[T], DocType[T][K][0]]> {
     const doc = await coll.findOne({
         domainId,
         docType,
diff --git a/packages/hydrooj/src/model/problem.ts b/packages/hydrooj/src/model/problem.ts
index f83590b10..edfc86e28 100644
--- a/packages/hydrooj/src/model/problem.ts
+++ b/packages/hydrooj/src/model/problem.ts
@@ -1,6 +1,6 @@
 import type { Readable } from 'stream';
 import { ObjectID, FilterQuery } from 'mongodb';
-import { Dictionary } from 'lodash';
+import { Dictionary, pick } from 'lodash';
 import { STATUS } from './builtin';
 import * as document from './document';
 import * as domain from './domain';
@@ -126,7 +126,7 @@ export function push<T extends ArrayKeys<Pdoc>>(domainId: string, _id: number, k
 }
 
 export function pull<T extends ArrayKeys<Pdoc>>(domainId: string, pid: number, key: ArrayKeys<Pdoc>, values: Pdoc[T][0][]) {
-    return document.pull(domainId, document.TYPE_PROBLEM, pid, key, values.map((_id) => ({ _id })));
+    return document.deleteSub(domainId, document.TYPE_PROBLEM, pid, key, values);
 }
 
 export function inc(domainId: string, _id: number, field: NumberKeys<Pdoc>, n: number): Promise<Pdoc> {
@@ -147,29 +147,35 @@ export function del(domainId: string, docId: number) {
 }
 
 export async function addTestdata(domainId: string, pid: number, name: string, f: Readable | Buffer | string) {
-    await storage.put(`problem/${domainId}/${pid}/testdata/${name}`, f);
+    const [current] = await Promise.all([
+        document.getSub(domainId, document.TYPE_PROBLEM, pid, 'data', name),
+        storage.put(`problem/${domainId}/${pid}/testdata/${name}`, f),
+    ]);
     const meta = await storage.getMeta(`problem/${domainId}/${pid}/testdata/${name}`);
-    return await push(domainId, pid, 'data', {
-        _id: name, name, size: meta.size, lastModified: meta.lastModified, etag: meta.etag,
-    });
+    const payload = { name, ...pick(meta, ['size', 'lastModified', 'etag']) };
+    if (!current) await push(domainId, pid, 'data', { _id: name, ...payload });
+    else await document.setSub(domainId, document.TYPE_PROBLEM, pid, 'data', name, payload);
 }
 
 export async function delTestdata(domainId: string, pid: number, name: string | string[]) {
-    const names = name instanceof Array ? name : [name];
+    const names = (name instanceof Array) ? name : [name];
     await storage.del(names.map((t) => `problem/${domainId}/${pid}/testdata/${t}`));
     await pull(domainId, pid, 'data', names);
 }
 
 export async function addAdditionalFile(domainId: string, pid: number, name: string, f: Readable | Buffer | string) {
-    await storage.put(`problem/${domainId}/${pid}/additional_file/${name}`, f);
+    const [[, fileinfo]] = await Promise.all([
+        document.getSub(domainId, document.TYPE_PROBLEM, pid, 'additional_file', name),
+        storage.put(`problem/${domainId}/${pid}/additional_file/${name}`, f),
+    ]);
     const meta = await storage.getMeta(`problem/${domainId}/${pid}/additional_file/${name}`);
-    return await push(domainId, pid, 'additional_file', {
-        _id: name, name, size: meta.size, lastModified: meta.lastModified, etag: meta.etag,
-    });
+    const payload = { name, ...pick(meta, ['size', 'lastModified', 'etag']) };
+    if (!fileinfo) await push(domainId, pid, 'additional_file', { _id: name, ...payload });
+    else await document.setSub(domainId, document.TYPE_PROBLEM, pid, 'additional_file', name, payload);
 }
 
 export async function delAdditionalFile(domainId: string, pid: number, name: string | string[]) {
-    const names = name instanceof Array ? name : [name];
+    const names = (name instanceof Array) ? name : [name];
     await storage.del(names.map((t) => `problem/${domainId}/${pid}/additional_file/${t}`));
     await pull(domainId, pid, 'additional_file', names);
 }