diff --git a/lib/app.js b/lib/app.js
index 34b90fd0f..8bac2d7a9 100644
--- a/lib/app.js
+++ b/lib/app.js
@@ -37,7 +37,7 @@ class App {
 
     return runOptionalFunction(plugins, 'open', {storageManager}, this.options)
       .then(() => queueHandler.run(urlSources))
-      .tap(() => runOptionalFunction(plugins, 'close', this.options));
+      .tap((errors) => runOptionalFunction(plugins, 'close', this.options, errors));
   }
 }
 
diff --git a/lib/plugins/slack/index.js b/lib/plugins/slack/index.js
index 366a5d7ef..fb5b67a2a 100644
--- a/lib/plugins/slack/index.js
+++ b/lib/plugins/slack/index.js
@@ -3,6 +3,7 @@
 let throwIfMissing = require('../../support/util').throwIfMissing,
   Promise = require('bluebird'),
   path = require('path'),
+  util = require('util'),
   merge = require('lodash.merge'),
   Slack = require('node-slack');
 
@@ -13,21 +14,27 @@ const defaultOptions = {
 };
 
 module.exports = {
-  name() { return path.basename(__dirname); },
+  name() {
+    return path.basename(__dirname);
+  },
   open(context, options) {
     throwIfMissing(options.slack, ['hookUrl', 'userName'], 'slack');
-
-    this.options = merge({}, defaultOptions, options.slack);
-    this.slack = new Slack(this.options.hookUrl);
-
-    if (!this.options.channel.startsWith('#'))
-      this.options.channel = '#' + this.options.channel;
   },
-  close() {
-    return this.slack.sendAsync({
-      text: 'Sitespeed done!',
-      channel: this.options.channel,
-      username: this.options.userName
+  close(errors, options) {
+    options = merge({}, defaultOptions, options.slack);
+    const slack = new Slack(options.hookUrl);
+
+    if (!options.channel.startsWith('#'))
+      options.channel = '#' + options.channel;
+
+    let text = 'Sitespeed done!';
+    if (errors.length > 0)
+      text += util.format(' (%d) errors', errors.length);
+
+    return slack.sendAsync({
+      text: text,
+      channel: options.channel,
+      username: options.userName
     });
   }
 };