--- a/testing/geckodriver/README.md
+++ b/testing/geckodriver/README.md
@@ -1,25 +1,37 @@
 # geckodriver [![Build Status](https://travis-ci.org/mozilla/geckodriver.svg?branch=release)](https://travis-ci.org/mozilla/geckodriver)
 
 Proxy for using W3C WebDriver-compatible clients
 to interact with Gecko-based browsers.
 
-This program provides the HTTP API described by
-the [WebDriver protocol](http://w3c.github.io/webdriver/webdriver-spec.html#protocol)
+This program provides the HTTP API described by the [WebDriver protocol]
 to communicate with Gecko browsers, such as Firefox.
-It translates calls into
-the [Marionette automation protocol](https://developer.mozilla.org/en-US/docs/Mozilla/QA/Marionette)
+It translates calls into the [Firefox remote protocol]
 by acting as a proxy between the local- and remote ends.
 
-You can consult the [change log](https://github.com/mozilla/geckodriver/blob/master/CHANGES.md)
-for a record of all notable changes to the program.
-[Releases](https://github.com/mozilla/geckodriver/releases)
-are made available on GitHub
-on [supported platforms](#supported-firefoxen).
+You can consult the [change log] for a record of all notable changes to the program.
+[Releases] are made available on GitHub on [supported platforms].
+
+The canonical source code repository for geckodriver
+now lives in [mozilla-central] under [testing/geckodriver].
+You can read more about [working with Mozilla source code] on MDN.
+This means we do no longer accept pull requests on GitHub.
+Patches should be uploaded to a bug
+in the [Testing :: GeckoDriver] component.
+
+[WebDriver protocol]: http://w3c.github.io/webdriver/webdriver-spec.html#protocol
+[Firefox remote protocol]: https://developer.mozilla.org/en-US/docs/Mozilla/QA/Marionette
+[change log]: https://github.com/mozilla/geckodriver/blob/master/CHANGES.md
+[Releases]: https://github.com/mozilla/geckodriver/releases
+[supported platforms]: #supported-firefoxen
+[mozilla-central]: https://hg.mozilla.org/mozilla-central/
+[testing/geckodriver]: https://hg.mozilla.org/mozilla-central/file/tip/testing/geckodriver
+[working with Mozilla source code]: https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Source_Code
+[Testing :: geckodriver]: https://bugzilla.mozilla.org/buglist.cgi?product=Testing&component=geckodriver&resolution=---&list_id=13613952
 
 ## Supported clients
 
 [Selenium](http://docs.seleniumhq.org/) users
 must update to [version 3.4](https://github.com/SeleniumHQ/selenium/releases/tag/selenium-3.4.0)
 or later to use geckodriver.
 Other clients that follow the [W3C WebDriver specification](https://w3c.github.io/webdriver/webdriver-spec.html) are also supported.
 
@@ -39,18 +51,18 @@ and [specification](https://github.com/m
 problems in our
 [issue tracker](https://github.com/mozilla/geckodriver/issues).
 
 Support is best in Firefox 53 and greater,
 although generally the more recent the Firefox version,
 the better the experience as they have more bug fixes and features.
 Some features will only be available in the most recent Firefox versions,
 and we strongly advise using the [latest Firefox Nightly](https://nightly.mozilla.org/) with geckodriver.
-Since Windows XP support was dropped with Firefox 53,
-geckodriver is not supported on this platform.
+Since Windows XP support in Firefox will be dropped with Firefox 53,
+we do not support this platform.
 
 ## WebDriver capabilities
 
 geckodriver supports a number of
 [WebDriver capabilities](https://w3c.github.io/webdriver/webdriver-spec.html#capabilities):
 
 <table>
  <thead>
@@ -528,8 +540,9 @@ Or if you want a non-optimised binary fo
 [webdriver crate]: https://github.com/mozilla/webdriver-rust
 [commands]: https://docs.rs/webdriver/0.25.0/webdriver/command/index.html
 [responses]: https://docs.rs/webdriver/0.25.0/webdriver/response/index.html
 [errors]: https://docs.rs/webdriver/0.25.0/webdriver/error/enum.ErrorStatus.html
 [Marionette protocol]: https://developer.mozilla.org/en-US/docs/Mozilla/QA/Marionette/Protocol
 [WebDriver]: https://w3c.github.io/webdriver/webdriver-spec.html
 [Marionette]: http://searchfox.org/mozilla-central/source/testing/marionette/README
 [Rust compiler toolchain]: https://rustup.rs/
+