diff --git a/.rubocop.yml b/.rubocop.yml
index a1d794f..031f834 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,5 +1,6 @@
 Metrics/BlockLength:
   Exclude:
+    - '*.gemspec'
     - 'spec/**/*'
 
 Metrics/ClassLength:
diff --git a/bin/tf b/bin/tf
index b82873a..abd2fcf 100755
--- a/bin/tf
+++ b/bin/tf
@@ -1,6 +1,6 @@
 #!/usr/bin/env ruby
 
-require 'bundler/setup' if File.exist? File.expand_path('../../Gemfile', __FILE__)
+require 'bundler/setup' if File.exist?(File.expand_path('../../Gemfile', __FILE__))
 require 'yle_tf/cli'
 
 cli = YleTf::CLI.new(ARGV)
diff --git a/lib/yle_tf/plugin/loader.rb b/lib/yle_tf/plugin/loader.rb
index c7823aa..cdbede8 100644
--- a/lib/yle_tf/plugin/loader.rb
+++ b/lib/yle_tf/plugin/loader.rb
@@ -19,10 +19,10 @@ def self.load_core_plugins
       end
 
       def self.load_bundler_plugins
-        if defined?(Bundler)
-          print_bundler_plugin_list if Logger.debug?
-          Bundler.require(BUNDLER_PLUGIN_GROUP)
-        end
+        return if !bundler_set_up?
+
+        Logger.debug { print_bundler_plugin_list }
+        Bundler.require(BUNDLER_PLUGIN_GROUP)
       end
 
       def self.load_user_plugins
@@ -47,6 +47,10 @@ def self.user_plugins
         ENV.fetch('TF_PLUGINS', '').split(/[ ,]+/)
       end
 
+      def self.bundler_set_up?
+        defined?(Bundler) && Bundler.respond_to?(:require)
+      end
+
       def self.print_bundler_plugin_list
         plugins = bundler_plugins
         if !plugins.empty?
diff --git a/yle_tf.gemspec b/yle_tf.gemspec
index 8e5c1a7..1f7fdb9 100644
--- a/yle_tf.gemspec
+++ b/yle_tf.gemspec
@@ -23,9 +23,9 @@ Gem::Specification.new do |spec|
     'antti.forsell@iki.fi',
   ]
 
-  spec.files = `git ls-files -z`.split("\x0").reject do |f|
-    f.match(%r{^(test|spec|features)/})
-  end
+  spec.files = Dir['bin/**/*'] +
+               Dir['lib/**/*.rb'] +
+               Dir['vendor/**/*']
 
   spec.bindir        = 'bin'
   spec.executables   = ['tf']