类型错误：connectToMongo 不是一个函数

我的代码 (Index.js)

const connectToMongo = require('./db')
connectToMongo();

我的代码 (db.js)

const mongoose = require('mongoose');
const mongoURI = "mongodb://localhost:27017"

const connectToMongo = ()=> {
    mongoose.connect(mongoURI,()=>{
        console.log("Connected to mongo successfully")
    })
}

module.export = connectToMongo;

有人可以帮忙吗？