diff --git a/install/ubuntu-1804.sh b/install/ubuntu-1804.sh
index 954f3c3e..f543922a 100644
--- a/install/ubuntu-1804.sh
+++ b/install/ubuntu-1804.sh
@@ -1,10 +1,11 @@
 #!/bin/bash
 
 # Basic
+apt-get update
+apt-get install curl wget unzip gnupg -y
 apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 9DA31620334BD75D9DCB49F368818C72E52529D4
 echo "deb [ arch=amd64 ] https://repo.mongodb.org/apt/ubuntu bionic/mongodb-org/4.0 multiverse" | tee /etc/apt/sources.list.d/mongodb-org-4.0.list
 apt-get update
-apt-get install curl wget unzip
 
 # Install MongoDB
 apt-get install -y mongodb-org
@@ -12,17 +13,20 @@ apt-get clean
 mkdir -p /data/db
 
 # Install NodeJS
-curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.36.0/install.sh | bash
-export $NVM_DIR=/root/.nvm
+curl -o- https://cdn.jsdelivr.net/gh/nvm-sh/nvm@v0.36.0/install.sh | sed 's/raw.githubusercontent.com\/nvm-sh\/nvm\//cdn.jsdelivr.net\/gh\/nvm-sh\/nvm@/g' | bash
+export NVM_DIR=/root/.nvm
 [ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"
 nvm install 14
 nvm use 14
 
 # Install HydroOJ
 npm i yarn -g
-yarn global add hydrooj @hydrooj/ui-default
+# TODO: install basic addons?
+yarn global add hydrooj @hydrooj/ui-default @hydrooj/hydrojudge
 
 # TODO: auto-config & start? pm2 daemon?
 
 # Finish
 echo "Done! use 'hydrooj' to start."
+
+# TODO: install judge
diff --git a/packages/fps-importer/handler.ts b/packages/fps-importer/handler.ts
index f0f381f0..b853b5c3 100644
--- a/packages/fps-importer/handler.ts
+++ b/packages/fps-importer/handler.ts
@@ -4,7 +4,7 @@ import os from 'os';
 import fs from 'fs-extra';
 import AdmZip from 'adm-zip';
 import xml2js from 'xml2js';
-import { ObjectID } from 'bson';
+import { ObjectID } from 'mongodb';
 import { filter } from 'lodash';
 import decodeHTML from 'decode-html';
 import { LocalProblemConfig } from 'hydrooj';