diff --git a/lib/docker_manager/upgrader.rb b/lib/docker_manager/upgrader.rb
index 24bb895..e2853eb 100644
--- a/lib/docker_manager/upgrader.rb
+++ b/lib/docker_manager/upgrader.rb
@@ -90,10 +90,6 @@ class DockerManager::Upgrader
       percent(20 * (index + 1) / @repos.size)
     end
 
-    bundler_version = parse_bundler_version
-    raise "Unable to determine bundler version from lockfile" if bundler_version.nil?
-    run("gem install bundler --conservative -v #{bundler_version}")
-
     run("bundle install --deployment --jobs 4 --without test development")
     begin
       run("bundle exec rake plugin:pull_compatible_all")
@@ -243,12 +239,6 @@ class DockerManager::Upgrader
 
   private
 
-  def parse_bundler_version
-    File.read("Gemfile.lock").lines.each_cons(2).find do |heading, version|
-      return version.strip if heading.strip == "BUNDLED WITH"
-    end
-  end
-
   def pid_exists?(pid)
     Process.getpgid(pid)
   rescue Errno::ESRCH