diff --git a/packages/hydrooj/package.json b/packages/hydrooj/package.json
index 9d400f700..2f5bfcc7b 100644
--- a/packages/hydrooj/package.json
+++ b/packages/hydrooj/package.json
@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "2.12.10",
+    "version": "2.12.11",
     "bin": "bin/hydrooj.js",
     "main": "dist/loader.js",
     "typings": "dist/loader.d.ts",
diff --git a/packages/hydrooj/src/entry/master.ts b/packages/hydrooj/src/entry/master.ts
index 81aaf5e75..72255459a 100644
--- a/packages/hydrooj/src/entry/master.ts
+++ b/packages/hydrooj/src/entry/master.ts
@@ -12,6 +12,7 @@ const tmpdir = path.resolve(os.tmpdir(), 'hydro');
 const lockfile = path.resolve(tmpdir, 'lock.json');
 
 export async function load(call: Entry) {
+    fs.ensureDirSync(tmpdir);
     if (fs.existsSync(lockfile) && !argv.ignorelock) {
         try {
             const file = require(lockfile);
diff --git a/packages/hydrooj/src/entry/setup.ts b/packages/hydrooj/src/entry/setup.ts
index e83f419cd..3a1cb31fe 100644
--- a/packages/hydrooj/src/entry/setup.ts
+++ b/packages/hydrooj/src/entry/setup.ts
@@ -52,6 +52,12 @@ class Loader {
                         <input name="name" type="text" value="hydro">
                       </label>
                     </div></div>
+                    <div class="row"><div class="columns">
+                      <label class="inverse material textbox">
+                        {{ _('Table Prefix') }}
+                        <input name="prefix" type="text" placeholder="{{ _('Leave blank if none') }}">>
+                      </label>
+                    </div></div>
                     <div class="row"><div class="columns">
                       <label class="inverse material textbox">
                         {{ _('Database Username') }}
@@ -103,7 +109,7 @@ async function get(ctx: Context) {
 
 async function post(ctx: Context) {
     const {
-        host, port, name, username, password,
+        host, port, name, username, password, prefix,
     } = ctx.request.body;
     let mongourl = 'mongodb://';
     if (username) mongourl += `${username}:${password}@`;
@@ -113,23 +119,24 @@ async function post(ctx: Context) {
             useNewUrlParser: true, useUnifiedTopology: true,
         });
         const db = Database.db(name);
+        const coll = prefix ? db.collection('system') : db.collection(`${prefix}.system`);
         await Promise.all([
-            db.collection('system').updateOne(
+            coll.updateOne(
                 { _id: 'server.host' },
                 { $set: { value: ctx.request.host } },
                 { upsert: true },
             ),
-            db.collection('system').updateOne(
+            coll.updateOne(
                 { _id: 'server.hostname' },
                 { $set: { value: ctx.request.hostname } },
                 { upsert: true },
             ),
-            db.collection('system').updateOne(
+            coll.updateOne(
                 { _id: 'server.url' },
                 { $set: { value: ctx.request.href } },
                 { upsert: true },
             ),
-            db.collection('system').updateOne(
+            coll.updateOne(
                 { _id: 'server.port' },
                 { $set: { value: parseInt(listenPort as string, 10) } },
                 { upsert: true },
diff --git a/packages/hydrooj/src/service/db.ts b/packages/hydrooj/src/service/db.ts
index 9dc5d780f..f23f5c8a6 100644
--- a/packages/hydrooj/src/service/db.ts
+++ b/packages/hydrooj/src/service/db.ts
@@ -19,6 +19,7 @@ mongodb.MongoClient.connect(mongourl, { useNewUrlParser: true, useUnifiedTopolog
     });
 
 export function collection(c: string) {
+    if (opts.prefix) return db.collection(`${opts.prefix}.${c}`);
     return db.collection(c);
 }