diff --git a/packages/hydrooj/src/handler/contest.ts b/packages/hydrooj/src/handler/contest.ts
index aa0683d97..89448a834 100644
--- a/packages/hydrooj/src/handler/contest.ts
+++ b/packages/hydrooj/src/handler/contest.ts
@@ -3,7 +3,9 @@ import { statSync } from 'fs-extra';
 import { pick } from 'lodash';
 import moment from 'moment-timezone';
 import { ObjectID } from 'mongodb';
-import { Counter, sortFiles, Time } from '@hydrooj/utils/lib/utils';
+import {
+    Counter, sortFiles, streamToBuffer, Time,
+} from '@hydrooj/utils/lib/utils';
 import {
     BadRequestError, ContestNotEndedError, ContestNotFoundError, ContestNotLiveError,
     ContestScoreboardHiddenError, FileLimitExceededError, FileUploadError, InvalidTokenError,
@@ -442,9 +444,18 @@ export class ContestCodeHandler extends Handler {
         const rdocs = await record.getMulti(domainId, {
             _id: { $in: Array.from(Object.keys(rnames)).map((id) => new ObjectID(id)) },
         }).toArray();
-        for (const rdoc of rdocs) {
-            zip.addFile(`${rnames[rdoc._id.toHexString()]}.${rdoc.lang}`, Buffer.from(rdoc.code));
-        }
+        await Promise.all(rdocs.map(async (rdoc) => {
+            if (rdoc.files?.code) {
+                const [id, filename] = rdoc.files?.code?.split('#') || [];
+                if (!id) return;
+                zip.addFile(
+                    `${rnames[rdoc._id.toHexString()]}.${filename || 'txt'}`,
+                    await streamToBuffer(storage.get(id)),
+                );
+            } else if (rdoc.code) {
+                zip.addFile(`${rnames[rdoc._id.toHexString()]}.${rdoc.lang}`, Buffer.from(rdoc.code));
+            }
+        }));
         this.binary(zip.toBuffer(), `${tdoc.title}.zip`);
     }
 }
diff --git a/packages/hydrooj/src/handler/problem.ts b/packages/hydrooj/src/handler/problem.ts
index 82a2f0751..f20c95e78 100644
--- a/packages/hydrooj/src/handler/problem.ts
+++ b/packages/hydrooj/src/handler/problem.ts
@@ -527,13 +527,13 @@ export class ProblemSubmitHandler extends ProblemDetailHandler {
             if (!file || file.size === 0) throw new ValidationError('code');
             const sizeLimit = config.type === 'submit_answer' ? 128 * 1024 * 1024 : 65535;
             if (file.size > sizeLimit) throw new ValidationError('file');
-            if (file.size > 65535 || await isBinaryFile(file.filepath, file.size)) {
+            if (config.type !== 'submit_answer' || (file.size < 65535 && !await isBinaryFile(file.filepath, file.size))) {
+                // TODO auto detect & convert encoding
+                code = await readFile(file.filepath, 'utf-8');
+            } else {
                 const id = nanoid();
                 await storage.put(`submission/${this.user._id}/${id}`, file.filepath, this.user._id);
                 files.code = `${this.user._id}/${id}#${file.originalFilename}`;
-            } else {
-                // TODO auto detect & convert encoding
-                code = await readFile(file.filepath, 'utf-8');
             }
         }
         const rid = await record.add(