diff --git a/types/conf/conf-tests.ts b/types/conf/conf-tests.ts
index 1da0e4de2d..ce67cd4799 100644
--- a/types/conf/conf-tests.ts
+++ b/types/conf/conf-tests.ts
@@ -4,18 +4,24 @@ const conf = new Conf<string | number | boolean>();
 new Conf<string>({
     defaults: {
         foo: 'bar',
-        unicorn: 'rainbow'
+        unicorn: 'rainbow',
     },
-    configName: '',
-    projectName: 'foo',
-    cwd: ''
 });
+new Conf<string>({ configName: '' });
+new Conf<string>({ projectName: 'foo' });
+new Conf<string>({ cwd: '' });
+new Conf<string>({ encryptionKey: '' });
+new Conf<string>({ encryptionKey: new Buffer('') });
+new Conf<string>({ encryptionKey: new Uint8Array([1]) });
+new Conf<string>({ encryptionKey: new DataView(new ArrayBuffer(2)) });
+new Conf<string>({ fileExtension: '.foo' });
+
 // $ExpectError
 new Conf<string>({
     defaults: {
         foo: 'bar',
-        unicorn: ['rainbow']
-    }
+        unicorn: ['rainbow'],
+    },
 });
 conf.set('foo', 'bar');
 conf.set('hello', 1);
@@ -28,10 +34,17 @@ conf.get('foo', null); // $ExpectError
 conf.delete('foo');
 conf.has('foo'); // $ExpectType boolean
 conf.clear();
+conf.onDidChange('foo', (oldVal, newVal) => {
+    // $ExpectType string | number | boolean | undefined
+    oldVal;
+    // $ExpectType string | number | boolean | undefined
+    newVal;
+});
 
+conf.size; // $ExpectType number
 conf.store = {
     foo: 'bar',
-    unicorn: 'rainbow'
+    unicorn: 'rainbow',
 };
 conf.path; // $ExpectType string
 
diff --git a/types/conf/index.d.ts b/types/conf/index.d.ts
index e58dc3ede7..57d7285a3e 100644
--- a/types/conf/index.d.ts
+++ b/types/conf/index.d.ts
@@ -1,31 +1,37 @@
-// Type definitions for conf 1.4
+// Type definitions for conf 2.1
 // Project: https://github.com/sindresorhus/conf
 // Definitions by: Sam Verschueren <https://github.com/SamVerschueren>
 //                 BendingBender <https://github.com/BendingBender>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
-interface Options<T> {
-	defaults?: {[key: string]: T};
-	configName?: string;
-	projectName?: string;
-	cwd?: string;
-}
+/// <reference types="node" />
 
 declare class Conf<T = any> implements Iterable<[string, T]> {
-	store: {[key: string]: T};
+    store: { [key: string]: T };
     readonly path: string;
-	readonly size: number;
+    readonly size: number;
 
-	constructor(options?: Options<T>);
-	get(key: string, defaultValue?: T): T;
-	set(key: string, val: T): void;
-	set(object: {[key: string]: T}): void;
-	has(key: string): boolean;
-	delete(key: string): void;
-	clear(): void;
-	onDidChange(key: string, callback: (oldVal: any, newVal: any) => void): void;
-	[Symbol.iterator](): Iterator<[string, T]>;
+    constructor(options?: Conf.Options<T>);
+    get(key: string, defaultValue?: T): T;
+    set(key: string, val: T): void;
+    set(object: { [key: string]: T }): void;
+    has(key: string): boolean;
+    delete(key: string): void;
+    clear(): void;
+    onDidChange(key: string, callback: (oldVal: T | undefined, newVal: T | undefined) => void): void;
+    [Symbol.iterator](): Iterator<[string, T]>;
+}
+
+declare namespace Conf {
+    interface Options<T> {
+        defaults?: { [key: string]: T };
+        configName?: string;
+        projectName?: string;
+        cwd?: string;
+        encryptionKey?: string | Buffer | NodeJS.TypedArray | DataView;
+        fileExtension?: string;
+    }
 }
 
 export = Conf;
diff --git a/types/conf/tsconfig.json b/types/conf/tsconfig.json
index 84d6bf7657..479fa6b41f 100644
--- a/types/conf/tsconfig.json
+++ b/types/conf/tsconfig.json
@@ -21,4 +21,4 @@
         "index.d.ts",
         "conf-tests.ts"
     ]
-}
\ No newline at end of file
+}
diff --git a/types/conf/v1/conf-tests.ts b/types/conf/v1/conf-tests.ts
new file mode 100644
index 0000000000..4ee492da8d
--- /dev/null
+++ b/types/conf/v1/conf-tests.ts
@@ -0,0 +1,41 @@
+import Conf = require('conf');
+
+const conf = new Conf<string | number | boolean>();
+new Conf<string>({
+    defaults: {
+        foo: 'bar',
+        unicorn: 'rainbow',
+    },
+    configName: '',
+    projectName: 'foo',
+    cwd: '',
+});
+// $ExpectError
+new Conf<string>({
+    defaults: {
+        foo: 'bar',
+        unicorn: ['rainbow'],
+    },
+});
+conf.set('foo', 'bar');
+conf.set('hello', 1);
+conf.set('unicorn', false);
+conf.set('null', null); // $ExpectError
+
+conf.get('foo'); // $ExpectType string | number | boolean
+conf.get('foo', 'bar'); // $ExpectType string | number | boolean
+conf.get('foo', null); // $ExpectError
+conf.delete('foo');
+conf.has('foo'); // $ExpectType boolean
+conf.clear();
+
+conf.store = {
+    foo: 'bar',
+    unicorn: 'rainbow',
+};
+conf.path; // $ExpectType string
+
+for (const [key, value] of conf) {
+    key; // $ExpectType string
+    value; // $ExpectType string | number | boolean
+}
diff --git a/types/conf/v1/index.d.ts b/types/conf/v1/index.d.ts
new file mode 100644
index 0000000000..f08cff1584
--- /dev/null
+++ b/types/conf/v1/index.d.ts
@@ -0,0 +1,31 @@
+// Type definitions for conf 1.4
+// Project: https://github.com/sindresorhus/conf
+// Definitions by: Sam Verschueren <https://github.com/SamVerschueren>
+//                 BendingBender <https://github.com/BendingBender>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.3
+
+interface Options<T> {
+    defaults?: { [key: string]: T };
+    configName?: string;
+    projectName?: string;
+    cwd?: string;
+}
+
+declare class Conf<T = any> implements Iterable<[string, T]> {
+    store: { [key: string]: T };
+    readonly path: string;
+    readonly size: number;
+
+    constructor(options?: Options<T>);
+    get(key: string, defaultValue?: T): T;
+    set(key: string, val: T): void;
+    set(object: { [key: string]: T }): void;
+    has(key: string): boolean;
+    delete(key: string): void;
+    clear(): void;
+    onDidChange(key: string, callback: (oldVal: any, newVal: any) => void): void;
+    [Symbol.iterator](): Iterator<[string, T]>;
+}
+
+export = Conf;
diff --git a/types/conf/v1/tsconfig.json b/types/conf/v1/tsconfig.json
new file mode 100644
index 0000000000..86b3a62f41
--- /dev/null
+++ b/types/conf/v1/tsconfig.json
@@ -0,0 +1,29 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "target": "es6",
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "strictFunctionTypes": true,
+        "baseUrl": "../../",
+        "typeRoots": [
+            "../../"
+        ],
+        "paths": {
+            "conf": [
+                "conf/v1"
+            ]
+        },
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "conf-tests.ts"
+    ]
+}
diff --git a/types/conf/v1/tslint.json b/types/conf/v1/tslint.json
new file mode 100644
index 0000000000..3db14f85ea
--- /dev/null
+++ b/types/conf/v1/tslint.json
@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }