diff --git a/ftp-srv.d.ts b/ftp-srv.d.ts
index 4b3231f..60b9c2e 100644
--- a/ftp-srv.d.ts
+++ b/ftp-srv.d.ts
@@ -1,44 +1,60 @@
-import * as tls from 'tls'
-import { Stats } from 'fs'
-import { EventEmitter } from 'events';
+import * as tls from "tls";
+import { Stats } from "fs";
+import { EventEmitter } from "events";
 
 export class FileSystem {
-
-	readonly connection: FtpConnection;
-	readonly root: string;
-	readonly cwd: string;
-
-    constructor(connection: FtpConnection, {root, cwd}?: {
-        root: any;
-        cwd: any;
-    });
-
-    currentDirectory(): string;
-
-    get(fileName: string): Promise<any>;
-
-    list(path?: string): Promise<any>;
-
-    chdir(path?: string): Promise<string>;
-
-    write(fileName: string, {append, start}?: {
-        append?: boolean;
-        start?: any;
-    }): any;
-
-    read(fileName: string, {start}?: {
-        start?: any;
-    }): Promise<any>;
-
-    delete(path: string): Promise<any>;
-
-    mkdir(path: string): Promise<any>;
-
-    rename(from: string, to: string): Promise<any>;
-
-    chmod(path: string, mode: string): Promise<any>;
-
-    getUniqueName(fileName: string): string;
+  readonly connection: FtpConnection;
+  readonly root: string;
+  readonly cwd: string;
+
+  constructor(
+    connection: FtpConnection,
+    {
+      root,
+      cwd,
+    }?: {
+      root: any;
+      cwd: any;
+    }
+  );
+
+  currentDirectory(): string;
+
+  get(fileName: string): Promise<any>;
+
+  list(path?: string): Promise<any>;
+
+  chdir(path?: string): Promise<string>;
+
+  write(
+    fileName: string,
+    {
+      append,
+      start,
+    }?: {
+      append?: boolean;
+      start?: any;
+    }
+  ): any;
+
+  read(
+    fileName: string,
+    {
+      start,
+    }?: {
+      start?: any;
+    }
+  ): Promise<any>;
+
+  delete(path: string): Promise<any>;
+
+  mkdir(path: string): Promise<any>;
+
+  rename(from: string, to: string): Promise<any>;
+
+  chmod(path: string, mode: string): Promise<any>;
+
+  getUniqueName(fileName: string): string;
 }
 
 export class GeneralError extends Error {
@@ -74,93 +90,101 @@ export class ConnectorError extends Error {
 }
 
 export class FtpConnection extends EventEmitter {
-	server: FtpServer;
-	id: string;
-	log: any;
-	transferType: string;
-	encoding: string;
-	bufferSize: boolean;
-	readonly ip: string;
-	restByteCount: number | undefined;
-	secure: boolean
-
-	close (code: number, message: number): Promise<any>
-	login (username: string, password: string): Promise<any>
-	reply (options: number | Object, ...letters: Array<any>): Promise<any>
-
+  server: FtpServer;
+  id: string;
+  log: any;
+  transferType: string;
+  encoding: string;
+  bufferSize: boolean;
+  readonly ip: string;
+  restByteCount: number | undefined;
+  secure: boolean;
+
+  close(code: number, message: number): Promise<any>;
+  login(username: string, password: string): Promise<any>;
+  reply(options: number | Object, ...letters: Array<any>): Promise<any>;
 }
 
 export interface FtpServerOptions {
-    url?: string,
-    pasv_min?: number,
-    pasv_max?: number,
-    pasv_url?: string,
-    greeting?: string | string[],
-    tls?: tls.SecureContextOptions | false,
-    anonymous?: boolean,
-    blacklist?: Array<string>,
-    whitelist?: Array<string>,
-    file_format?: (stat: Stats) => string | Promise<string> | "ls" | "ep",
-	log?: any,
-	timeout?: number
+  url?: string;
+  pasv_min?: number;
+  pasv_max?: number;
+  pasv_url?: string;
+  greeting?: string | string[];
+  tls?: tls.SecureContextOptions | false;
+  anonymous?: boolean;
+  blacklist?: Array<string>;
+  whitelist?: Array<string>;
+  file_format?: (stat: Stats) => string | Promise<string> | "ls" | "ep";
+  log?: any;
+  timeout?: number;
 }
 
 export class FtpServer extends EventEmitter {
-    constructor(options?: FtpServerOptions);
-
-    readonly isTLS: boolean;
-
-    listen(): any;
-
-    emitPromise(action: any, ...data: any[]): Promise<any>;
-
-    // emit is exported from super class
-
-    setupTLS(_tls: boolean): boolean | {
-      cert: string;
-      key: string;
-      ca: string
-    };
-
-    setupGreeting(greet: string): string[];
-
-    setupFeaturesMessage(): string;
-
-    disconnectClient(id: string): Promise<any>;
-
-    close(): any;
-
-	on(event: "login", listener: (
-		data: {
-			connection: FtpConnection,
-			username: string,
-			password: string
-		},
-		resolve: (config: {
-            fs?: FileSystem,
-            root?: string,
-            cwd?: string,
-            blacklist?: Array<string>,
-            whitelist?: Array<string>
-        }) => void,
-		reject: (err?: Error) => void
-  ) => void): this;
-
-	on(event: "disconnect", listener: (
-		data: {
-      connection: FtpConnection,
-      id: string
-		}
-	) => void): this;
-
-	on(event: "client-error", listener: (
-		data: {
-			connection: FtpConnection,
-			context: string,
-			error: Error,
-		}
-	) => void): this;
+  constructor(options?: FtpServerOptions);
+
+  readonly isTLS: boolean;
+
+  listen(): any;
+
+  emitPromise(action: any, ...data: any[]): Promise<any>;
+
+  // emit is exported from super class
+
+  setupTLS(_tls: boolean):
+    | boolean
+    | {
+        cert: string;
+        key: string;
+        ca: string;
+      };
+
+  setupGreeting(greet: string): string[];
+
+  setupFeaturesMessage(): string;
+
+  disconnectClient(id: string): Promise<any>;
+
+  close(): any;
+
+  on(
+    event: "login",
+    listener: (
+      data: {
+        connection: FtpConnection;
+        username: string;
+        password: string;
+      },
+      resolve: (config: {
+        fs?: FileSystem;
+        root?: string;
+        cwd?: string;
+        blacklist?: Array<string>;
+        whitelist?: Array<string>;
+      }) => void,
+      reject: (err?: Error) => void
+    ) => void
+  ): this;
+
+  on(
+    event: "connect",
+    listener: (data: { connection: FtpConnection; id: string; newConnectionCount: number }) => void
+  ): this;
+
+  on(
+    event: "disconnect",
+    listener: (data: { connection: FtpConnection; id: string; newConnectionCount: number }) => void
+  ): this;
+
+  on(
+    event: "client-error",
+    listener: (data: {
+      connection: FtpConnection;
+      context: string;
+      error: Error;
+    }) => void
+  ): this;
 }
 
-export {FtpServer as FtpSrv};
+export { FtpServer as FtpSrv };
 export default FtpServer;
diff --git a/ftp-srv.js b/ftp-srv.js
index b700858..7393db2 100644
--- a/ftp-srv.js
+++ b/ftp-srv.js
@@ -1,8 +1,14 @@
-const FtpSrv = require('./src');
+const FtpServer = require('./src');
+const FtpConnection = require('./src/connection');
 const FileSystem = require('./src/fs');
 const errors = require('./src/errors');
 
-module.exports = FtpSrv;
-module.exports.FtpSrv = FtpSrv;
+module.exports = FtpServer;
+module.exports.FtpSrv = FtpServer;
+module.exports.FtpServer = FtpServer;
 module.exports.FileSystem = FileSystem;
-module.exports.ftpErrors = errors;
+module.exports.GeneralError = errors.GeneralError;
+module.exports.SocketError = errors.SocketError;
+module.exports.FileSystemError = errors.FileSystemError;
+module.exports.ConnectorError = errors.ConnectorError;
+module.exports.FtpConnection = FtpConnection;
diff --git a/src/index.js b/src/index.js
index 859540d..ff36f73 100644
--- a/src/index.js
+++ b/src/index.js
@@ -25,8 +25,7 @@ class FtpServer extends EventEmitter {
       greeting: null,
       tls: false,
       timeout: 0
-    }, options);
-
+    }, _.pickBy(options, v => v !== undefined));
     this._greeting = this.setupGreeting(this.options.greeting);
     this._features = this.setupFeaturesMessage();
 
@@ -52,7 +51,7 @@ class FtpServer extends EventEmitter {
       socket.once('close', () => {
         this.emit('disconnect', {connection, id: connection.id, newConnectionCount: Object.keys(this.connections).length});
       })
-      
+
       this.emit('connect', {connection, id: connection.id, newConnectionCount: Object.keys(this.connections).length});
 
       const greeting = this._greeting || [];
@@ -67,7 +66,7 @@ class FtpServer extends EventEmitter {
       this.log.error(err, '[Event] error');
       this.emit('server-error', {error: err});
     });
-    
+
     const quit = _.debounce(this.quit.bind(this), 100);
 
     process.on('SIGTERM', quit);
@@ -138,7 +137,7 @@ class FtpServer extends EventEmitter {
       } catch (err) {
         this.log.error(err, 'Error closing connection', {id});
       }
-      
+
       resolve('Disconnected');
     });
   }