diff --git a/igdm.js b/instagram.js
similarity index 67%
rename from igdm.js
rename to instagram.js
index 96b7882..f37de14 100644
--- a/igdm.js
+++ b/instagram.js
@@ -1,49 +1,34 @@
-const fs = require('fs');
 const Client = require('instagram-private-api').V1;
-let storage, device;
+const utils = require('./utils');
 
-exports.checkAuth = function () {
+exports.checkAuth = function (session) {
   return new Promise((resolve, reject) => {
-    let files = fs.readdirSync(`${__dirname}/cookies`);
-
-    if (files.length && files[0].endsWith('.json')) {
-      let filename = files[0]
-      device = new Client.Device(filename.slice(0, -5)); // remove .json extension
-      storage = new Client.CookieFileStorage(`${__dirname}/cookies/${filename}`);
-
-      const session = new Client.Session(device, storage);
-      // see if IG allows this session to make request
-      return session.getAccountId()
-        .then(() => resolve({ isLoggedIn: true, session }))
-        .catch(Client.Exceptions.CookieNotValidError, () => resolve({ isLoggedIn: false }))
-    } else {
-      resolve({ isLoggedIn: false })
+    if (!session) {
+      const device = utils.getDevice();
+      const storage = utils.getCookieStorage();
+      if (!device || !storage) {
+        return resolve({ isLoggedIn: false });
+      }
+      session = new Client.Session(device, storage);
     }
-  })
+
+    session.getAccountId()
+      .then(() => resolve({ isLoggedIn: true, session }))
+      .catch(Client.Exceptions.CookieNotValidError, () => resolve({ isLoggedIn: false }))
+  });
 }
 
 exports.login = function (username, password) {
-  // delete all session storage
-  let files = fs.readdirSync(`${__dirname}/cookies`);
-  files.forEach((filename) => {
-    fs.unlinkSync(`${__dirname}/cookies/${filename}`);
-  })
-
+  utils.clearCookieFiles();
   return new Promise((resolve, reject) => {
-    // create file
-    device = new Client.Device(username);
-    storage = new Client.CookieFileStorage(`${__dirname}/cookies/${username}.json`);
-
+    const device = utils.getDevice(username);
+    const storage = utils.getCookieStorage(`${__dirname}/cookies/${username}.json`);
     Client.Session.create(device, storage, username, password).then(resolve).catch(reject)
   })
 }
 
 exports.logout = function () {
-  // delete all session storage
-  let files = fs.readdirSync(`${__dirname}/cookies`);
-  files.forEach((filename) => {
-    fs.unlinkSync(`${__dirname}/cookies/${filename}`);
-  })
+  utils.clearCookieFiles();
 }
 
 exports.getChatList = function (session) {
diff --git a/main.js b/main.js
index 332cb94..431d2c8 100644
--- a/main.js
+++ b/main.js
@@ -5,7 +5,7 @@ const menuTemplate = require('./menutemplate');
 const BrowserWindow = electron.BrowserWindow;
 const path = require('path');
 const url = require('url');
-const igdm = require('./igdm');
+const instagram = require('./instagram');
 const autoUpdater = require('./autoupdater');
 const notifier = require('node-notifier');
 let pollingInterval = 10000;
@@ -39,7 +39,7 @@ function createWindow () {
   }
   mainWindow.setTitle('Desktop IG:dm')
 
-  igdm.checkAuth().then((result) => {
+  instagram.checkAuth(session).then((result) => {
     let view = result.isLoggedIn ? 'browser/index.html' : 'browser/login.html'
     session = result.session || session
 
@@ -54,7 +54,7 @@ function createWindow () {
 }
 
 function getChatList () {
-  igdm.getChatList(session).then((chats) => {
+  instagram.getChatList(session).then((chats) => {
     mainWindow.webContents.send('chatList', chats)
 
     setTimeout(getChatList, pollingInterval);
@@ -63,7 +63,7 @@ function getChatList () {
 
 let timeoutObj;
 function getChat (evt, id) {
-  igdm.getChat(session, id).then((chat) => {
+  instagram.getChat(session, id).then((chat) => {
     mainWindow.webContents.send('chat', chat);
 
     if (timeoutObj) clearTimeout(timeoutObj)
@@ -103,14 +103,14 @@ app.on('browser-window-focus', () => {
 })
 
 electron.ipcMain.on('login', (evt, data) => {
-  igdm.login(data.username, data.password).then((session_) => {
+  instagram.login(data.username, data.password).then((session_) => {
     session = session_
     createWindow()
   }).catch(() => createWindow())
 })
 
 electron.ipcMain.on('logout', (evt, data) => {
-  igdm.logout()
+  instagram.logout()
   session = null
   createWindow()
 })
@@ -125,19 +125,19 @@ electron.ipcMain.on('getChatList', getChatList)
 electron.ipcMain.on('getChat', getChat)
 
 electron.ipcMain.on('message', (evt, data) => {
-  igdm.sendMessage(session, data.message, data.users).then((chat) => {
+  instagram.sendMessage(session, data.message, data.users).then((chat) => {
     if (data.isNewChat) getChat(null, chat[0].id)
   })
 })
 
 electron.ipcMain.on('searchUsers', (evt, search) => {
-  igdm.searchUsers(session, search).then((users) => {
+  instagram.searchUsers(session, search).then((users) => {
     mainWindow.webContents.send('searchResult', users);
   })
 })
 
 electron.ipcMain.on('markAsRead', (evt, thread) => {
-  igdm.seen(session, thread)
+  instagram.seen(session, thread)
 })
 
 electron.ipcMain.on('notify', (evt, message) => {
@@ -147,11 +147,11 @@ electron.ipcMain.on('notify', (evt, message) => {
 })
 
 electron.ipcMain.on('getUnfollowers', (evt) => {
-  igdm.getUnfollowers(session).then((users) => {
+  instagram.getUnfollowers(session).then((users) => {
     mainWindow.webContents.send('unfollowers', users)
   })
 })
 
 electron.ipcMain.on('unfollow', (evt, userId) => {
-  igdm.unfollow(session, userId)
+  instagram.unfollow(session, userId)
 })
diff --git a/utils.js b/utils.js
new file mode 100644
index 0000000..6b29854
--- /dev/null
+++ b/utils.js
@@ -0,0 +1,60 @@
+const fs = require('fs');
+const Client = require('instagram-private-api').V1;
+
+const canUseFileStorage = () => {
+  try {
+    fs.accessSync(`${__dirname}/cookies/`, fs.W_OK);
+    return true
+  } catch (error) {
+    return false
+  }
+}
+
+const guessUsername = () => {
+  let username;
+  if (canUseFileStorage()) {
+    const files = fs.readdirSync(`${__dirname}/cookies`);
+    if (files.length && files[0].endsWith('.json')) {
+      username = files[0].slice(0, -5);
+    }
+  }
+  return username;
+}
+
+const getCookieStorage = (filePath) => {
+  let storage;
+  let username;
+
+  if (canUseFileStorage()) {
+    if (!filePath && (username = guessUsername())) {
+      filePath = `${__dirname}/cookies/${username}.json`  
+    }
+
+    if (filePath) storage = new Client.CookieFileStorage(filePath);
+  } else {
+    storage = new Client.CookieMemoryStorage();
+  }
+
+  return storage;
+}
+
+const clearCookieFiles = () => {
+  // delete all session storage
+  if (canUseFileStorage()) {
+    fs.readdirSync(`${__dirname}/cookies`).forEach((filename) => {
+      fs.unlinkSync(`${__dirname}/cookies/${filename}`);
+    })
+  }
+}
+
+const getDevice = (username) => {
+  let device;
+  username = username || guessUsername();
+  if (username) device = new Client.Device(username);
+  return device;
+}
+
+module.exports = {
+    canUseFileStorage, guessUsername,
+    getCookieStorage, clearCookieFiles, getDevice
+}