diff --git a/index.d.ts b/index.d.ts
index b61027f..eee2e83 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,4 +1,3 @@
-/// <reference types="node"/>
 import * as stream from 'stream';
 
 declare const isStream: {
diff --git a/index.js b/index.js
index a8d571f..2e43434 100644
--- a/index.js
+++ b/index.js
@@ -23,7 +23,6 @@ isStream.duplex = stream =>
 
 isStream.transform = stream =>
 	isStream.duplex(stream) &&
-	typeof stream._transform === 'function' &&
-	typeof stream._transformState === 'object';
+	typeof stream._transform === 'function';
 
 module.exports = isStream;
diff --git a/test.js b/test.js
index d2e61e3..6cf9653 100644
--- a/test.js
+++ b/test.js
@@ -27,10 +27,10 @@ test('isStream.writable()', t => {
 	t.true(isStream.writable(new Stream.Transform()));
 	t.true(isStream.writable(new Stream.PassThrough()));
 	t.true(isStream.writable(fs.createWriteStream(tempy.file())));
+	t.true(isStream.writable(new net.Socket()));
 	t.false(isStream.writable(new Stream.Stream()));
 	t.false(isStream.writable(new Stream.Readable()));
 	t.false(isStream.writable(fs.createReadStream('test.js')));
-	t.false(isStream.writable(new net.Socket()));
 });
 
 test('isStream.readable()', t => {
@@ -39,10 +39,10 @@ test('isStream.readable()', t => {
 	t.true(isStream.readable(new Stream.Transform()));
 	t.true(isStream.readable(new Stream.PassThrough()));
 	t.true(isStream.readable(fs.createReadStream('test.js')));
+	t.true(isStream.readable(new net.Socket()));
 	t.false(isStream.readable(new Stream.Stream()));
 	t.false(isStream.readable(new Stream.Writable()));
 	t.false(isStream.readable(fs.createWriteStream(tempy.file())));
-	t.false(isStream.readable(new net.Socket()));
 });
 
 test('isStream.duplex()', t => {