diff --git a/README.md b/README.md
index 724b3ba..16cc393 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ function doStuff(x, y) {
 and your function `doStuff` will behave the same as a Web IDL operation declared as
 
 ```webidl
-void doStuff(boolean x, unsigned long y);
+undefined doStuff(boolean x, unsigned long y);
 ```
 
 ## API
@@ -48,7 +48,7 @@ Specific conversions may also accept other options, the details of which can be
 Conversions for all of the basic types from the Web IDL specification are implemented:
 
 - [`any`](https://heycam.github.io/webidl/#es-any)
-- [`void`](https://heycam.github.io/webidl/#es-void)
+- [`undefined`](https://heycam.github.io/webidl/#es-undefined)
 - [`boolean`](https://heycam.github.io/webidl/#es-boolean)
 - [Integer types](https://heycam.github.io/webidl/#es-integer-types), which can additionally be provided the boolean options `{ clamp, enforceRange }` as a second parameter
 - [`float`](https://heycam.github.io/webidl/#es-float), [`unrestricted float`](https://heycam.github.io/webidl/#es-unrestricted-float)
diff --git a/lib/index.js b/lib/index.js
index d38e8d5..0229347 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -167,7 +167,7 @@ exports.any = value => {
   return value;
 };
 
-exports.void = () => {
+exports.undefined = () => {
   return undefined;
 };
 
diff --git a/test/void.js b/test/undefined.js
similarity index 86%
rename from test/void.js
rename to test/undefined.js
index 07a1f55..61ec398 100644
--- a/test/void.js
+++ b/test/undefined.js
@@ -3,8 +3,8 @@ const assert = require("assert");
 
 const conversions = require("..");
 
-describe("WebIDL void type", () => {
-  const sut = conversions.void;
+describe("WebIDL undefined type", () => {
+  const sut = conversions.undefined;
 
   it("should return `undefined` for everything", () => {
     assert.strictEqual(sut(undefined), undefined);