diff --git a/CHANGELOG.md b/CHANGELOG.md
index e97dd0f2..987750a7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## l20n 6.0.0 (Deprecated)
+
+L20n.js has been deprecated and is no longer maintained. Please use
+[Fluent](https://projectfluent.org), the successor to L20n developed by the
+same team at Mozilla. Fluent is a mature localization system currently used in
+Firefox and in many other Mozilla projects.
+
+Code-wise, `l20n.js` 6.0.0 is the same as 5.0.0. We're publishing it as a major
+version to reduce disruptions which may result from the deprecation. Only
+version 6.0.0 has been deprecated on npm. Existing projects using earlier
+versions won't receive deprecation warnings when running `npm install`.
+
 ## l20n 5.0.0
 
 Starting with this release, `l20n` is built on top of Project Fluent. `l20n`
@@ -27,7 +39,7 @@ As of this release (v5), the version of `fluent` used is `0.3.1`.  There are a f
 updates to the syntax compared to `l20n` v4:
 
   - Multiline text is now simply indented and doesn't require the pipe `|`
-    prefix. See http://projectfluent.io/fluent/guide/text.html.
+    prefix. See http://projectfluent.org/fluent/guide/text.html.
 
     Before:
 
@@ -43,7 +55,7 @@ updates to the syntax compared to `l20n` v4:
 
   - Attributes are now written using the dot `.` prefix instead of the square
     brackets. The placement of the equals sign `=` is also different. See
-    http://projectfluent.io/fluent/guide/attributes.html.
+    http://projectfluent.org/fluent/guide/attributes.html.
 
     Before:
 
@@ -56,7 +68,7 @@ updates to the syntax compared to `l20n` v4:
             .title = Hello, world!
 
   - Comments are now written with the double forward slash `//` prefix instead
-    of the hash `#`.  See http://projectfluent.io/fluent/guide/comments.html
+    of the hash `#`.  See http://projectfluent.org/fluent/guide/comments.html
 
     Before:
 
@@ -70,7 +82,7 @@ updates to the syntax compared to `l20n` v4:
 
   - Select expressions must now define the default variant. The whole body of
     the expression must be intended too (we might lift this requirement in the
-    future). See http://projectfluent.io/fluent/guide/selectors.html.
+    future). See http://projectfluent.org/fluent/guide/selectors.html.
 
     Before:
 
@@ -96,7 +108,7 @@ updates to the syntax compared to `l20n` v4:
 
   - Traits were removed in favor of attributes (see above) and variants known
     from select expressions. See
-    http://projectfluent.io/fluent/guide/variants.html
+    http://projectfluent.org/fluent/guide/variants.html
 
     Before:
 
diff --git a/README.md b/README.md
index 17e7cf4c..05e3397b 100644
--- a/README.md
+++ b/README.md
@@ -1,18 +1,22 @@
-L20n: Localization 2.0 [![Build Status][travisimage]][travislink]
-=================================================================
+L20n: Localization 2.0 (Deprecated)
+===================================
 
-[travisimage]: https://travis-ci.org/l20n/l20n.js.svg?branch=master
-[travislink]: https://travis-ci.org/l20n/l20n.js
+__L20n.js has been deprecated and is no longer maintained. Please use
+[Fluent][], the successor to L20n developed by the same team at Mozilla.
+Fluent is a mature localization system currently used in Firefox and in many
+other Mozilla projects.__
 
-L20n is an opinionated localization library for the Web.  It builds on top of
-[Project Fluent][] which was designed to unleash the expressive power of the
-natural language.
+---
+
+L20n is an opinionated localization library for the Web. It builds on top of
+[Fluent][] which was designed to unleash the expressive power of the natural
+language.
 
 L20n.js is a good choice for websites which want to offer a best-in-class
 translation experience for their users.  L20n takes advantage of modern web
 technologies to offer a fast and lean localization of HTML and JavaScript.
 
-[Project Fluent]: http://projectfluent.io
+[Fluent]: http://projectfluent.org
 
 
 How to use L20n
@@ -61,5 +65,5 @@ and others.
 [Read the Fluent Syntax Guide][] in order to learn more about the syntax.  If
 you're a tool author you may be interested in the formal [EBNF grammar][].
 
-[Read the Fluent Syntax Guide]: http://projectfluent.io/fluent/guide/
+[Read the Fluent Syntax Guide]: http://projectfluent.org/fluent/guide/
 [EBNF grammar]: https://github.com/projectfluent/fluent/tree/master/spec
diff --git a/package.json b/package.json
index 7942f214..ba75f89a 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "l20n",
   "description": "A localization library for HTML documents",
-  "version": "5.0.0",
+  "version": "6.0.0",
   "homepage": "http://l20n.org",
   "author": "Mozilla <l10n-drivers@mozilla.org>",
   "license": "Apache-2.0",