diff --git a/src/index.ts b/src/index.ts
index 01b9d2944b..b61283b4e9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -23,7 +23,6 @@ import notesStats from './daemons/notes-stats';
 import loadConfig from './config/load';
 import { Config } from './config/types';
 import { lessThan } from './prelude/array';
-import { Db } from 'mongodb';
 
 const clusterLog = debug('misskey:cluster');
 const ev = new Xev();
@@ -192,38 +191,35 @@ async function init(): Promise<Config> {
 	}
 
 	// Try to connect to MongoDB
-	//await checkMongoDB(config);
+	await checkMongoDB(config);
 
 	return config;
 }
 
 const requiredMongoDBVersion = [3, 6];
 
-function checkMongoDB(config: Config): Promise<void> {
+function checkMongoDB(config: Config) {
 	const mongoDBLogger = new Logger('MongoDB');
 	const u = config.mongodb.user ? encodeURIComponent(config.mongodb.user) : null;
 	const p = config.mongodb.pass ? encodeURIComponent(config.mongodb.pass) : null;
 	const uri = `mongodb://${u && p ? `${u}:****@` : ''}${config.mongodb.host}:${config.mongodb.port}/${config.mongodb.db}`;
 	mongoDBLogger.info(`Connecting to ${uri}`);
 
-	return mongo.then(async () => {
+	mongo.then(() => {
 		mongoDBLogger.succ('Connectivity confirmed');
 
-		const runningMongoDBVersion = (await nativeDbConn().then(getMongoDBVersion)).split('.').map(x => parseInt(x, 10));
-		mongoDBLogger.info(`Version: ${runningMongoDBVersion.join('.')}`);
-		if (lessThan(runningMongoDBVersion, requiredMongoDBVersion)) {
-			mongoDBLogger.error(`MongoDB version is less than ${requiredMongoDBVersion.join('.')}. Please upgrade it.`);
-			process.exit(1);
-		}
+		nativeDbConn().then(db => db.admin().serverInfo()).then(x => x.version).then((version: string) => {
+			mongoDBLogger.info(`Version: ${version}`);
+			if (lessThan(version.split('.').map(x => parseInt(x, 10)), requiredMongoDBVersion)) {
+				mongoDBLogger.error(`MongoDB version is less than ${requiredMongoDBVersion.join('.')}. Please upgrade it.`);
+				process.exit(1);
+			}
+		});
 	}).catch(err => {
 		mongoDBLogger.error(err.message);
 	});
 }
 
-async function getMongoDBVersion(db: Db): Promise<string> {
-	return (await db.admin().serverInfo()).version;
-}
-
 async function spawnWorkers(limit: number = Infinity) {
 	const workers = Math.min(limit, os.cpus().length);
 	Logger.info(`Starting ${workers} worker${workers === 1 ? '' : 's'}...`);