diff --git a/objectid.d.ts b/objectid.d.ts
index f164893..6e0c78a 100644
--- a/objectid.d.ts
+++ b/objectid.d.ts
@@ -1,29 +1,37 @@
-// Type definitions for bson-objectid 1.3.1
-// Project: bson-objectid
-// Definitions by: Marcel Ernst <https://www.marcel-ernst.de>
-import { Buffer } from 'buffer';
-export default ObjectID;
-
-declare class ObjectID {
-    static createFromTime(time: number): ObjectID;
-    static createFromHexString(hexString: string): ObjectID;
-    static isValid(hexString: string):boolean;
-    static isValid(ObjectID: ObjectID):boolean;
-    static generate(): string;
-    static generate(time: number): string;
-    static toString():string;
-
-    constructor();
-    constructor(time: number);
-    constructor(hexString: string);
-    constructor(idString: string);
-    constructor(array: number[]);
-    constructor(buffer: Buffer);
-
-    readonly id: string;
-    readonly str: string;
-
-    toHexString(): string;
-    equals(other: ObjectID): boolean;
-    getTimestamp(): number;
+import {Buffer} from 'buffer';
+
+export default ObjectID
+
+declare const ObjectID: ObjectIDCtor;
+
+declare interface ObjectID {
+  readonly id: string;
+  readonly str: string;
+
+  toHexString(): string;
+  equals(other: ObjectID): boolean;
+  getTimestamp(): number;
+}
+
+declare interface ObjectIDCtor {
+  (): ObjectID
+  (time: number): ObjectID
+  (hexString: string): ObjectID
+  (idString: string): ObjectID
+  (array: number[]): ObjectID
+  (buffer: Buffer): ObjectID
+
+  new(): ObjectID
+  new(time: number): ObjectID
+  new(hexString: string): ObjectID
+  new(idString: string): ObjectID
+  new(array: number[]): ObjectID
+  new(buffer: Buffer): ObjectID
+
+
+  createFromTime(time: number): ObjectID;
+  createFromHexString(hexString: string): ObjectID;
+  isValid(hexString: string): boolean;
+  isValid(ObjectID: ObjectID): boolean;
+  toString(): string;
 }
diff --git a/typing-tests/objectid-tests.ts b/typing-tests/objectid-tests.ts
index 8188b8d..25c1c8f 100644
--- a/typing-tests/objectid-tests.ts
+++ b/typing-tests/objectid-tests.ts
@@ -50,6 +50,38 @@ oid = ObjectID.createFromTime(time);
 // should construct with `ObjectID.createFromHexString(hexString)`
 oid = ObjectID.createFromHexString(hexString);
 
+// ----------------------------------------------------------------------------
+// should construct with no arguments
+oid = ObjectID();
+
+// ----------------------------------------------------------------------------
+// should have an `id` property
+oid.id;
+
+// ----------------------------------------------------------------------------
+// should have a `str` property
+oid.str;
+
+// ----------------------------------------------------------------------------
+// should construct with a `time` argument
+oid = ObjectID(time);
+
+// ----------------------------------------------------------------------------
+// should construct with an `array` argument
+oid = ObjectID(array);
+
+// ----------------------------------------------------------------------------
+// should construct with a `buffer` argument
+oid = ObjectID(buffer);
+
+// ----------------------------------------------------------------------------
+// should construct with a `hexString` argument
+oid = ObjectID(hexString);
+
+// ----------------------------------------------------------------------------
+// should construct with a `idString` argument
+oid = ObjectID(idString);
+
 // ----------------------------------------------------------------------------
 // should correctly retrieve timestamp
 const timestamp:number = oid.getTimestamp();