diff --git a/packages/hydrooj/package.json b/packages/hydrooj/package.json
index 281bdf04c..6c1f555fc 100644
--- a/packages/hydrooj/package.json
+++ b/packages/hydrooj/package.json
@@ -1,6 +1,6 @@
 {
     "name": "hydrooj",
-    "version": "4.1.0",
+    "version": "4.1.1",
     "bin": "bin/hydrooj.js",
     "main": "src/plugin-api",
     "module": "src/plugin-api",
diff --git a/packages/hydrooj/src/handler/manage.ts b/packages/hydrooj/src/handler/manage.ts
index e5ce1bd0b..931e9efff 100644
--- a/packages/hydrooj/src/handler/manage.ts
+++ b/packages/hydrooj/src/handler/manage.ts
@@ -286,10 +286,11 @@ class SystemUserPrivHandler extends SystemHandler {
     }
 
     @requireSudo
-    @param('uid', Types.Int, true)
+    @param('uid', Types.Int)
     @param('priv', Types.UnsignedInt)
-    async post(domainId: string, uid: number, priv: number) {
-        if (typeof uid === 'number') {
+    @param('system', Types.Boolean, true)
+    async post(domainId: string, uid: number, priv: number, editSystem: boolean) {
+        if (!editSystem) {
             const udoc = await user.getById(domainId, uid);
             if (!udoc) throw new UserNotFoundError(uid);
             if (udoc.priv === -1 || priv === -1 || priv === allPriv) throw new ForbiddenError('you can not edit user as SU in web.');
diff --git a/packages/ui-default/components/selectUser.ts b/packages/ui-default/components/selectUser.ts
index 49c384f27..d6e29a163 100644
--- a/packages/ui-default/components/selectUser.ts
+++ b/packages/ui-default/components/selectUser.ts
@@ -4,37 +4,36 @@ import i18n from 'vj/utils/i18n';
 import tpl from 'vj/utils/tpl';
 import createHint from './hint';
 
-let inserted = false;
+let hintInserted = false;
+$(tpl`<div style="display: none" class="dialog__body--user-select">
+  <div class="row"><div class="columns">
+    <h1 name="select_user_hint">${i18n('Select User')}</h1>
+  </div></div>
+  <div class="row">
+    <div class="columns">
+      <label>${i18n('Username / UID')}
+        <input name="user" type="text" class="textbox" autocomplete="off" data-autofocus>
+      </label>
+    </div>
+  </div>
+</div>`).appendTo(document.body);
+const userSelector = UserSelectAutoComplete.getOrConstruct($('.dialog__body--user-select [name="user"]')) as any;
+const userSelectDialog = new ActionDialog({
+  $body: $('.dialog__body--user-select > div'),
+  onDispatch(action) {
+    if (action === 'ok' && userSelector.value() === null) {
+      userSelector.focus();
+      return false;
+    }
+    return true;
+  },
+});
 
 export default async function selectUser(hint?: string) {
-  if (!inserted) {
-    const el = $(tpl`<div style="display: none" class="dialog__body--user-select">
-      <div class="row"><div class="columns">
-        <h1 name="select_user_hint">${i18n('Select User')}</h1>
-      </div></div>
-      <div class="row">
-        <div class="columns">
-          <label>${i18n('Username / UID')}
-            <input name="user" type="text" class="textbox" autocomplete="off" data-autofocus>
-          </label>
-        </div>
-      </div>
-    </div>`);
-    el.appendTo(document.body);
-    if (hint) createHint(hint, $('[name="select_user_hint"]'));
-    inserted = true;
+  if (hint && !hintInserted) {
+    createHint(hint, $('[name="select_user_hint"]'));
+    hintInserted = true;
   }
-  const userSelector = UserSelectAutoComplete.getOrConstruct($('.dialog__body--user-select [name="user"]')) as any;
-  const userSelectDialog = new ActionDialog({
-    $body: $('.dialog__body--user-select > div'),
-    onDispatch(action) {
-      if (action === 'ok' && userSelector.value() === null) {
-        userSelector.focus();
-        return false;
-      }
-      return true;
-    },
-  });
   userSelector.clear();
   const action = await userSelectDialog.open();
   if (action !== 'ok') return null;
diff --git a/packages/ui-default/package.json b/packages/ui-default/package.json
index 9301fa422..3221ca503 100644
--- a/packages/ui-default/package.json
+++ b/packages/ui-default/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hydrooj/ui-default",
-  "version": "4.41.16",
+  "version": "4.41.17",
   "author": "undefined <i@undefined.moe>",
   "license": "AGPL-3.0",
   "main": "index.ts",
diff --git a/packages/ui-default/pages/manage_user_priv.page.js b/packages/ui-default/pages/manage_user_priv.page.js
index aa5f132fd..b64a65507 100644
--- a/packages/ui-default/pages/manage_user_priv.page.js
+++ b/packages/ui-default/pages/manage_user_priv.page.js
@@ -20,10 +20,11 @@ const page = new NamedPage('manage_user_priv', () => {
 
   async function changeUserPriv(uid, priv) {
     try {
-      const res = await request.post('', uid !== 'default' ? {
-        uid,
+      const res = await request.post('', {
+        uid: uid !== 'default' ? uid : 0,
         priv,
-      } : { priv });
+        system: uid === 'default',
+      });
       if (res.url && res.url !== window.location.href) window.location.href = res.url;
       else {
         Notification.success(i18n('Priv has been updated to {0}.', priv));
@@ -54,8 +55,8 @@ const page = new NamedPage('manage_user_priv', () => {
     handleOpenUserPrivDialog(user.udoc);
   }
 
-  $('[name="select_user"]').on('click', () => handleClickSelectUser());
-  $('[name="set_priv"]').on('click', (ev) => handleOpenUserPrivDialog(ev));
+  $(document).on('click', '[name="select_user"]', () => handleClickSelectUser());
+  $(document).on('click', '[name="set_priv"]', (ev) => handleOpenUserPrivDialog(ev));
 });
 
 export default page;