diff --git a/.gitignore b/.gitignore
index 0cb6eeb..b827cff 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,4 +6,5 @@
 /doc/
 /pkg/
 /spec/reports/
+/spec/examples.txt
 /tmp/
diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000..437459c
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+2.5.0
diff --git a/.travis.yml b/.travis.yml
index bb45ab6..bdf3580 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,5 @@
 language: ruby
 rvm:
-  - 2.1.9
-  - 2.2.5
-  - 2.3.1
+  - 2.4.1
+  - 2.5.0
 before_install: gem update bundler
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..9ba175e
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,10 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+### Added
+- Ability to specify `last_id` of a channel
+- Get access to `message_id` if specified in the callback
diff --git a/Gemfile b/Gemfile
index a7f86bd..a550366 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,3 +2,5 @@ source 'https://rubygems.org'
 
 # Specify your gem's dependencies in message_bus-client.gemspec
 gemspec
+
+gem "pry-byebug"
diff --git a/README.md b/README.md
index 02f36d3..58be5de 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ The API is mostly equivalent with the JavaScript client:
 
 ```ruby
 client = MessageBus::Client.new('http://chat.samsaffron.com/')
-client.subscribe('/message') do |payload|
+client.subscribe('/message') do |payload, message_id|
   # Do stuff
 end
 
diff --git a/Rakefile b/Rakefile
index 7c6aacf..bde1bec 100644
--- a/Rakefile
+++ b/Rakefile
@@ -11,9 +11,18 @@ task :server do
   end
 
   at_exit do
-    $stderr.puts "Killing pid #{pid}"
-    Process.kill('KILL', pid)
-    Process.wait(pid)
+    if RbConfig::CONFIG["host_os"] =~ /mswin|mingw/
+      $stderr.puts "Killing pid #{pid}"
+      Process.kill('KILL', pid)
+      Process.wait(pid)
+    else
+      child_pid = `pgrep -P #{pid}`.to_i
+      pids = [child_pid, pid]
+      pids.each do |pid|
+        $stderr.puts "Killing pid #{pid}"
+        Process.kill('KILL', pid)
+      end
+    end
   end
 
   sleep 3
diff --git a/lib/message_bus/client.rb b/lib/message_bus/client.rb
index 5bb8184..709e5a1 100644
--- a/lib/message_bus/client.rb
+++ b/lib/message_bus/client.rb
@@ -1,5 +1,6 @@
 require 'excon'
 require 'json'
+require "securerandom"
 
 require 'message_bus/client/version'
 require 'message_bus/client/configuration'
diff --git a/lib/message_bus/client/message_handler.rb b/lib/message_bus/client/message_handler.rb
index 71bb0bc..08d6fc1 100644
--- a/lib/message_bus/client/message_handler.rb
+++ b/lib/message_bus/client/message_handler.rb
@@ -1,13 +1,13 @@
 module MessageBus::Client::MessageHandler
   SubscribedChannel = Struct.new(:callbacks, :last_id) do
-    def initialize(last_id = -1)
+    def initialize(last_id)
       self.callbacks = []
       self.last_id = last_id
     end
 
-    def callback(payload)
+    def callback(payload, message_id)
       callbacks.each do |callback|
-        callback.call(payload)
+        callback.call(payload, message_id)
       end
     end
   end
@@ -20,14 +20,16 @@ def initialize(base_url)
 
     @pending_messages = []
     @subscribed_channels = {}
-    @subscribed_channels.default_proc = proc do |hash, key|
-      hash[key] = SubscribedChannel.new
-    end
     @payload = String.new
   end
 
-  def subscribe(channel, &callback)
-    @subscribed_channels[channel].callbacks << callback
+  def subscribe(channel, last_id=-1, &callback)
+    subscribed_channel = @subscribed_channels[channel]
+    if subscribed_channel.nil?
+      subscribed_channel = @subscribed_channels[channel] =
+        SubscribedChannel.new(last_id)
+    end
+    subscribed_channel.callbacks << callback
   end
 
   def unsubscribe
@@ -80,8 +82,9 @@ def handle_message(message)
     subscription = @subscribed_channels[message['channel']]
     return unless subscription
 
-    subscription.last_id = message['message_id']
-    subscription.callback(message['data'])
+    message_id = message['message_id']
+    subscription.last_id = message_id
+    subscription.callback(message['data'], message_id)
   end
 
   def handle_status_message(message)
diff --git a/spec/coverage_helper.rb b/spec/coverage_helper.rb
deleted file mode 100644
index 27fee81..0000000
--- a/spec/coverage_helper.rb
+++ /dev/null
@@ -1,65 +0,0 @@
-# Simultaneous code coverage reporting to Coveralls and Code Climate.
-# Latest version can be found at https://gist.github.com/lowjoel/6c2f2d3a08bb3786994f
-require 'simplecov'
-
-module CoverageHelper
-  class << self
-    # Helper to include Coveralls/Code Climate coverage, but not require developers to install the
-    # gem.
-    #
-    # @param [String] name The name of the module to require.
-    # @param [Proc] initializer The block to execute when the module is required successfully.
-    def load(name, &initializer)
-      old_formatter = SimpleCov.formatter
-      require name
-      initializer.call
-
-      merge_formatters(old_formatter, SimpleCov.formatter)
-    rescue LoadError => e
-      if e.path == name
-        puts format('Cannot find \'%s\', ignoring', name) if ENV['CI']
-      else
-        raise e
-      end
-    end
-
-    private
-
-    # Merge two SimpleCov formatters into a single MultiFormatter.
-    #
-    # This method is idempotent if the old and new formatters are the same.
-    def merge_formatters(old_formatter, new_formatter)
-      return if old_formatter == new_formatter
-
-      old_formatter = [*expand_formatter(old_formatter)]
-      new_formatter = [*expand_formatter(new_formatter)]
-      formatters = old_formatter + new_formatter
-
-      SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter.new(formatters)
-    end
-
-    # Extracts the formatters from a MultiFormatter so we do not nest them.
-    def expand_formatter(formatter)
-      return formatter unless formatter.is_a?(SimpleCov::Formatter::MultiFormatter)
-      formatter.formatters
-    end
-  end
-end
-
-if ENV['CI']
-  # Coveralls
-  CoverageHelper.load('coveralls') do
-    Coveralls.wear!('rails')
-  end
-
-  # Code Climate
-  CoverageHelper.load('codeclimate-test-reporter') do
-    CodeClimate::TestReporter.start
-  end
-
-  # Code coverage exclusions
-  SimpleCov.start do
-    # SimpleCov configuration
-    # add_filter '/lib/extensions/active_record/connection_adapters/table_definition.rb'
-  end
-end
diff --git a/spec/message_bus/client_spec.rb b/spec/message_bus/client_spec.rb
index 26511de..809a5dd 100644
--- a/spec/message_bus/client_spec.rb
+++ b/spec/message_bus/client_spec.rb
@@ -37,7 +37,7 @@ def write_message(message, user = 'message_bus-client')
       end
     end
 
-    it 'receives messages' do
+    it 'receives new messages by default (last_id of -1)' do
       subject.start
 
       text = "Hello World! #{Random.rand}"
@@ -72,7 +72,7 @@ def write_message(message, user = 'message_bus-client')
       subject.stop
     end
 
-    it 'receives messages' do
+    it 'receives new messages by default (last_id of -1)' do
       subject.start
 
       text = "Hello World! #{Random.rand}"
@@ -113,4 +113,20 @@ def write_message(message, user = 'message_bus-client')
     subject.resume
     expect(result).to eq(true)
   end
+
+  it 'allows subscription exposing the message_id' do
+    subject.start
+
+    text = "Hello World! #{Random.rand}"
+    result = false
+    subject.subscribe('/message') do |payload, message_id|
+      result = true if payload['data'] == text
+      expect(message_id).to be_an Integer
+    end
+
+    until result
+      write_message(text) # Keep writing because the message bus might not have started.
+      sleep(1)
+    end
+  end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 81db7d9..febe631 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,6 +1,6 @@
 $LOAD_PATH.unshift File.expand_path('../../lib', __FILE__)
-require 'coverage_helper'
 require 'message_bus/client'
+require "pry-byebug"
 
 # This file was generated by the `rspec --init` command. Conventionally, all
 # specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.