diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index f14cfb99..7664f6c3 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -6,14 +6,6 @@
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 15
-# Cop supports --auto-correct.
-# Configuration parameters: Include, TreatCommentsAsGroupSeparators.
-# Include: **/Gemfile, **/gems.rb
-Bundler/OrderedGems:
-  Exclude:
-    - 'Gemfile'
-
 # Offense count: 1
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle, SupportedStyles, IndentationWidth.
@@ -646,16 +638,6 @@ Style/RedundantParentheses:
   Exclude:
     - 'app/controllers/admin/base_controller.rb'
 
-# Offense count: 9
-# Cop supports --auto-correct.
-# Configuration parameters: AllowMultipleReturnValues.
-Style/RedundantReturn:
-  Exclude:
-    - 'app/helpers/application_helper.rb'
-    - 'app/helpers/format_helper.rb'
-    - 'app/helpers/paths_helper.rb'
-    - 'app/helpers/users_helper.rb'
-
 # Offense count: 2
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle, SupportedStyles, AllowInnerSlashes.
@@ -740,10 +722,3 @@ Style/TrailingCommaInLiteral:
     - 'Guardfile'
     - 'db/migrate/20140701123203_add_events_per_week_to_conference.rb'
     - 'spec/models/conference_spec.rb'
-
-# Offense count: 3
-# Cop supports --auto-correct.
-Style/UnneededInterpolation:
-  Exclude:
-    - 'app/helpers/format_helper.rb'
-    - 'spec/controllers/admin/conferences_controller_spec.rb'
diff --git a/Gemfile b/Gemfile
index d4e3f517..0806088d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -27,8 +27,8 @@ gem 'paper_trail'
 
 # for upload management
 gem 'carrierwave'
-gem 'mini_magick'
 gem 'carrierwave-bombshelter'
+gem 'mini_magick'
 
 # for internationalizing
 gem 'rails-i18n', '~> 4.0.0'
@@ -40,9 +40,9 @@ gem 'devise_ichain_authenticatable'
 # for openID authentication
 gem 'omniauth'
 gem 'omniauth-facebook'
-gem 'omniauth-openid'
-gem 'omniauth-google-oauth2'
 gem 'omniauth-github'
+gem 'omniauth-google-oauth2'
+gem 'omniauth-openid'
 
 # Bot-filtering
 gem 'recaptcha', require: 'recaptcha/rails'
@@ -60,8 +60,8 @@ gem 'unobtrusive_flash', '>=3'
 gem 'transitions', :require => %w( transitions active_record/transitions )
 
 # for comments
-gem 'awesome_nested_set', '~> 3.1.3'
 gem 'acts_as_commentable_with_threading'
+gem 'awesome_nested_set', '~> 3.1.3'
 
 # as templating language
 gem 'haml-rails'
@@ -73,11 +73,11 @@ gem 'sass-rails', '>= 4.0.2'
 gem 'uglifier', '>= 1.3.0'
 
 # as the front-end framework
-gem 'bootstrap-sass', '~> 3.3.4.1'
 gem 'autoprefixer-rails'
-gem 'formtastic-bootstrap'
-gem 'formtastic', '~> 3.1.1'
+gem 'bootstrap-sass', '~> 3.3.4.1'
 gem 'cocoon'
+gem 'formtastic', '~> 3.1.1'
+gem 'formtastic-bootstrap'
 
 # as the JavaScript library
 gem 'jquery-rails'
@@ -108,8 +108,8 @@ source 'https://rails-assets.org' do
   gem 'rails-assets-waypoints'
   # for markdown editors
   gem 'rails-assets-bootstrap-markdown'
-  gem 'rails-assets-to-markdown'
   gem 'rails-assets-markdown'
+  gem 'rails-assets-to-markdown'
 end
 
 # as date picker
@@ -129,9 +129,9 @@ gem 'gravtastic'
 gem 'country_select'
 
 # as PDF generator
+gem 'prawn-qrcode', '~> 0.2.2.1'
 gem 'prawn_rails'
 gem 'rqrcode'
-gem 'prawn-qrcode', '~> 0.2.2.1'
 
 # to render XLS spreadsheets
 gem 'axlsx', git: 'https://github.com/randym/axlsx.git'
@@ -156,13 +156,13 @@ gem 'redcarpet'
 gem 'rdoc-generator-fivefish'
 
 # for visitor tracking
-gem 'ahoy_matey'
 gem 'activeuuid'
+gem 'ahoy_matey'
 gem 'piwik_analytics', '~> 1.0.1'
 
 # for recurring jobs
-gem 'whenever', :require => false
 gem 'delayed_job_active_record'
+gem 'whenever', :require => false
 
 # to run scripts
 gem 'daemons'
@@ -216,8 +216,8 @@ gem 'nokogiri', '>= 1.8.1'
 group :development do
   # to launch specs when files are modified
   gem 'guard-rspec'
-  gem 'spring-commands-rspec'
   gem 'haml_lint', '~> 0.24.0'
+  gem 'spring-commands-rspec'
   # for static code analisys
   gem 'rubocop', '~> 0.51.0', require: false
   # as database
@@ -234,11 +234,11 @@ end
 
 group :test do
   # as test framework
-  gem 'rspec-rails', '~> 3.5', '>= 3.5.2'
-  gem 'database_cleaner'
   gem 'capybara'
-  gem 'poltergeist'
+  gem 'database_cleaner'
   gem 'phantomjs', :require => 'phantomjs/poltergeist'
+  gem 'poltergeist'
+  gem 'rspec-rails', '~> 3.5', '>= 3.5.2'
   # for measuring test coverage
   gem 'coveralls', require: false
   # for describing models
diff --git a/INSTALL.md b/INSTALL.md
index 29dc5cec..7da0c52c 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -42,7 +42,7 @@ There are two configurations to deploy OSEM with Docker: *evaluation mode* and *
 
 If you want to evaluate OSEM to see if it fits your needs, the default configuration in `docker-compose.env` will work perfectly fine for you.
 For convenience reasons, `docker-compose.yml` already contains a [MailHog](https://github.com/mailhog/MailHog) service configuration. MailHog
-is going to catch every email sent by OSEM and displays them on a special web service. Thus, it eliminitates the need to set up an SMTP server just to try out OSEM.
+is going to catch every email sent by OSEM and displays them on a special web service. Thus, it eliminates the need to set up an SMTP server just to try out OSEM.
 Just point your browser to http://localhost:8025 to get access to registration confirmation links etc.
 
 Run `docker-compose up --build` to start the services. On first run, it will take a few minutes to initialize the database. Thus, wait a few minutes before you open up
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index b5e2892e..b1e249ba 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -66,7 +66,7 @@ module ApplicationHelper
     else
       ts = all.join
     end
-    return ts
+    ts
   end
 
   def difficulty_levels(conference)
@@ -80,7 +80,7 @@ module ApplicationHelper
     else
       ts = all.join
     end
-    return ts
+    ts
   end
 
   def unread_notifications(user)
diff --git a/app/helpers/format_helper.rb b/app/helpers/format_helper.rb
index 65578ba6..a41c584e 100644
--- a/app/helpers/format_helper.rb
+++ b/app/helpers/format_helper.rb
@@ -101,17 +101,17 @@ module FormatHelper
 
   def icon_for_todo(bool)
     if bool
-      return 'fa fa-check'
+      'fa fa-check'
     else
-      return 'fa fa-times'
+      'fa fa-times'
     end
   end
 
   def class_for_todo(bool)
     if bool
-      return 'todolist-ok'
+      'todolist-ok'
     else
-      return 'todolist-missing'
+      'todolist-missing'
     end
   end
 
@@ -122,7 +122,7 @@ module FormatHelper
              plural || singular.pluralize
            end
 
-    "#{word}"
+    word
   end
 
   # Returns black or white deppending on what of them contrast more with the
diff --git a/app/helpers/paths_helper.rb b/app/helpers/paths_helper.rb
index df01ab2f..46e82900 100644
--- a/app/helpers/paths_helper.rb
+++ b/app/helpers/paths_helper.rb
@@ -5,9 +5,9 @@ module PathsHelper
 
   def active_nav_li(link)
     if current_page?(link)
-      return 'active'
+      'active'
     else
-      return ''
+      ''
     end
   end
 end
diff --git a/app/helpers/users_helper.rb b/app/helpers/users_helper.rb
index 50becf0c..763a44c9 100644
--- a/app/helpers/users_helper.rb
+++ b/app/helpers/users_helper.rb
@@ -18,7 +18,7 @@ module UsersHelper
       providers << provider if !ENV["OSEM_#{provider.upcase}_KEY"].blank? && !ENV["OSEM_#{provider.upcase}_SECRET"].blank?
     end
 
-    return providers.uniq
+    providers.uniq
   end
 
   # Receives a hash, generated from User model, function get_roles
diff --git a/spec/controllers/admin/conferences_controller_spec.rb b/spec/controllers/admin/conferences_controller_spec.rb
index 009e40ba..ff9d676b 100644
--- a/spec/controllers/admin/conferences_controller_spec.rb
+++ b/spec/controllers/admin/conferences_controller_spec.rb
@@ -56,8 +56,8 @@ describe Admin::ConferencesController do
           conference.reload
           expect(flash[:error])
               .to eq("Updating conference failed. Short title can't be blank.")
-          expect(conference.title).to eq("#{conference.title}")
-          expect(conference.short_title).to eq("#{conference.short_title}")
+          expect(conference.title).to eq(conference.title)
+          expect(conference.short_title).to eq(conference.short_title)
         end
 
         it 're-renders the #show template' do