diff --git a/main/app.ts b/main/app.ts
index 98c7fbf..1c526b2 100644
--- a/main/app.ts
+++ b/main/app.ts
@@ -1,19 +1,10 @@
-import * as path from 'path';
 import {app, Menu, globalShortcut, Tray} from 'electron';
 import log from './log';
 import {Config, Account} from './config';
 import AccountSwitcher from './account_switcher';
 import defaultMenu from './default_menu';
 import Window from './window';
-
-const IS_DARWIN = process.platform === 'darwin';
-const APP_ICON = path.join(__dirname, '..', 'resources', 'icon', 'icon.png');
-
-function trayIcon(color: string) {
-    return path.join(__dirname, '..', 'resources', 'icon', `tray-icon-${
-        color === 'white' ? 'white' : 'black'
-    }@2x.png`);
-}
+import {IS_DARWIN, APP_ICON, trayIcon} from './common';
 
 export class App {
     private switcher: AccountSwitcher;
diff --git a/main/common.ts b/main/common.ts
new file mode 100644
index 0000000..54176a9
--- /dev/null
+++ b/main/common.ts
@@ -0,0 +1,16 @@
+import * as path from 'path';
+import {app} from 'electron';
+
+export const IS_DEBUG = process.env.NODE_ENV === 'development';
+export const IS_DARWIN = process.platform === 'darwin';
+export const APP_ICON = path.join(__dirname, '..', 'resources', 'icon', 'icon.png');
+export const PRELOAD_JS = path.join(__dirname, '..', 'renderer', 'preload.js');
+export const DATA_DIR = app.getPath('userData');
+export const CONFIG_FILE = path.join(DATA_DIR, 'config.json');
+
+export function trayIcon(color: string) {
+    return path.join(__dirname, '..', 'resources', 'icon', `tray-icon-${
+        color === 'white' ? 'white' : 'black'
+    }@2x.png`);
+}
+
diff --git a/main/config.ts b/main/config.ts
index 9789b5c..f50c3b0 100644
--- a/main/config.ts
+++ b/main/config.ts
@@ -1,7 +1,7 @@
 import {app, systemPreferences, dialog, shell} from 'electron';
 import * as fs from 'fs';
-import {join} from 'path';
 import log from './log';
+import {CONFIG_FILE} from './common';
 
 export interface Account {
     host: string;
@@ -68,22 +68,20 @@ function recommendConfigAndDie(file: string) {
 
 export default function loadConfig(): Promise<Config> {
     return new Promise<Config>(resolve => {
-        const dir = app.getPath('userData');
-        const file = join(dir, 'config.json');
-        fs.readFile(file, 'utf8', (err, json) => {
+        fs.readFile(CONFIG_FILE, 'utf8', (err, json) => {
             if (err) {
-                log.info('Configuration file was not found, will create:', file);
+                log.info('Configuration file was not found, will create:', CONFIG_FILE);
                 const default_config = makeDefaultConfig();
                 // Note:
                 // If calling writeFile() directly here, it tries to create config file before Electron
                 // runtime creates data directory. As the result, writeFile() would fail to create a file.
                 if (app.isReady()) {
-                    fs.writeFileSync(file, JSON.stringify(default_config, null, 2));
-                    recommendConfigAndDie(file);
+                    fs.writeFileSync(CONFIG_FILE, JSON.stringify(default_config, null, 2));
+                    recommendConfigAndDie(CONFIG_FILE);
                 } else {
                     app.once('ready', () => {
-                        fs.writeFileSync(file, JSON.stringify(default_config, null, 2));
-                        recommendConfigAndDie(file);
+                        fs.writeFileSync(CONFIG_FILE, JSON.stringify(default_config, null, 2));
+                        recommendConfigAndDie(CONFIG_FILE);
                     });
                 }
                 return;
@@ -96,7 +94,7 @@ export default function loadConfig(): Promise<Config> {
                 }
                 log.debug('Configuration was loaded successfully', config);
                 if (!config.accounts || config.accounts[0].host === '' || config.accounts[0].name === '') {
-                    recommendConfigAndDie(file);
+                    recommendConfigAndDie(CONFIG_FILE);
                 } else {
                     resolve(config);
                 }
diff --git a/main/window.ts b/main/window.ts
index 418f634..3b11dfa 100644
--- a/main/window.ts
+++ b/main/window.ts
@@ -1,15 +1,10 @@
-import * as path from 'path';
 import {app, BrowserWindow, globalShortcut, shell, dialog, Menu} from 'electron';
 import windowState = require('electron-window-state');
 import * as menubar from 'menubar';
 import {Config, Account} from './config';
 import {partitionForAccount} from './account_switcher';
 import log from './log';
-
-const IS_DEBUG = process.env.NODE_ENV === 'development';
-const IS_DARWIN = process.platform === 'darwin';
-const APP_ICON = path.join(__dirname, '..', 'resources', 'icon', 'icon.png');
-const PRELOAD_JS = path.join(__dirname, '..', 'renderer', 'preload.js');
+import {IS_DEBUG, IS_DARWIN, APP_ICON, PRELOAD_JS, trayIcon} from './common';
 
 export default class Window {
     static create(account: Account, config: Config, mb: Menubar.MenubarApp | null = null) {
@@ -84,12 +79,6 @@ export default class Window {
     }
 }
 
-function trayIcon(color: string) {
-    return path.join(__dirname, '..', 'resources', 'icon', `tray-icon-${
-        color === 'white' ? 'white' : 'black'
-    }@2x.png`);
-}
-
 function startNormalWindow(account: Account, config: Config): Promise<Window> {
     log.debug('Setup a normal window');
     return new Promise<Window>(resolve => {