diff --git a/README.md b/README.md
index db2f1344..cd03dfa8 100644
--- a/README.md
+++ b/README.md
@@ -149,6 +149,17 @@ For a good example, see https://riot.im/develop/config.json
with referral tracking; please ignore it.
1. `welcomeUserId`: the user ID of a bot to invite whenever users register that can give them a tour
+
+Note that `index.html` also has an og:image meta tag that is set to an image
+hosted on riot.im. This is the image used if links to your copy of Riot
+appear in some websites like Facebook, and indeed Riot itself. This has to be
+static in the HTML and an absolute URL (and HTTP rather than HTTPS), so it's
+not possible for this to be an option in config.json. If you'd like to change
+it, you can build Riot as above, but run
+`RIOT_OG_IMAGE_URL="http://example.com/logo.png" npm run build`.
+Alternatively, you can edit the `og:image` meta tag in `index.html` directly
+each time you download a new version of Riot.
+
Running as a Desktop app
========================
diff --git a/src/vector/index.html b/src/vector/index.html
index d05fb4d0..91d28642 100644
--- a/src/vector/index.html
+++ b/src/vector/index.html
@@ -20,7 +20,7 @@
-
+
<% for (var i=0; i < htmlWebpackPlugin.files.css.length; i++) {
var file = htmlWebpackPlugin.files.css[i];
var match = file.match(/^bundles\/.*?\/theme-(.*)\.css$/);
diff --git a/webpack.config.js b/webpack.config.js
index 2df82d9b..0f7691c6 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -3,6 +3,9 @@ const webpack = require('webpack');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
+let og_image_url = process.env.RIOT_OG_IMAGE_URL;
+if (!og_image_url) og_image_url = 'https://riot.im/app/img/logos/riot-im-logo-1.png';
+
module.exports = {
entry: {
"bundle": "./src/vector/index.js",
@@ -123,6 +126,9 @@ module.exports = {
// bottom of or the bottom of , and I'm a bit scared
// about moving them.
inject: false,
+ vars: {
+ og_image_url: og_image_url,
+ },
}),
],
devtool: 'source-map',