diff --git a/node/node.d.ts b/node/node.d.ts
index 07e1120d4..9500b0123 100644
--- a/node/node.d.ts
+++ b/node/node.d.ts
@@ -351,13 +351,13 @@ declare module "zlib" {
     export interface InflateRaw extends stream.ReadWriteStream { }
     export interface Unzip extends stream.ReadWriteStream { }
 
-    export function createGzip(options: ZlibOptions): Gzip;
-    export function createGunzip(options: ZlibOptions): Gunzip;
-    export function createDeflate(options: ZlibOptions): Deflate;
-    export function createInflate(options: ZlibOptions): Inflate;
-    export function createDeflateRaw(options: ZlibOptions): DeflateRaw;
-    export function createInflateRaw(options: ZlibOptions): InflateRaw;
-    export function createUnzip(options: ZlibOptions): Unzip;
+    export function createGzip(options?: ZlibOptions): Gzip;
+    export function createGunzip(options?: ZlibOptions): Gunzip;
+    export function createDeflate(options?: ZlibOptions): Deflate;
+    export function createInflate(options?: ZlibOptions): Inflate;
+    export function createDeflateRaw(options?: ZlibOptions): DeflateRaw;
+    export function createInflateRaw(options?: ZlibOptions): InflateRaw;
+    export function createUnzip(options?: ZlibOptions): Unzip;
 
     export function deflate(buf: NodeBuffer, callback: (error: Error, result: any) =>void ): void;
     export function deflateRaw(buf: NodeBuffer, callback: (error: Error, result: any) =>void ): void;