diff --git a/app/models/auth_provider.rb b/app/models/auth_provider.rb
index e54b0766a..25df71439 100644
--- a/app/models/auth_provider.rb
+++ b/app/models/auth_provider.rb
@@ -1,5 +1,6 @@
-class AuthProvider < ActiveRecord::Base
+# frozen_string_literal: true
 
+class AuthProvider < ActiveRecord::Base
   # this is a simple stub used for database creation & configuration
   class SimpleAuthProvider < Object
     def providable_type
diff --git a/app/validators/file_mime_type_validator.rb b/app/validators/file_mime_type_validator.rb
index 43c384521..7e25e2562 100644
--- a/app/validators/file_mime_type_validator.rb
+++ b/app/validators/file_mime_type_validator.rb
@@ -1,11 +1,12 @@
+# frozen_string_literal: true
+
 # Based on: https://gist.github.com/1298417
-
 class FileMimeTypeValidator < ActiveModel::EachValidator
-  MESSAGES  = { :content_type => :wrong_content_type }.freeze
-  CHECKS    = [ :content_type ].freeze
+  MESSAGES  = { content_type: :wrong_content_type }.freeze
+  CHECKS    = [:content_type].freeze
 
-  DEFAULT_TOKENIZER = lambda { |value| value.split(//) }
-  RESERVED_OPTIONS  = [:content_type, :tokenizer]
+  DEFAULT_TOKENIZER = ->(value) { value.split(//) }
+  RESERVED_OPTIONS  = %i[content_type tokenizer].freeze
 
   def initialize(options)
     super
@@ -14,33 +15,29 @@ class FileMimeTypeValidator < ActiveModel::EachValidator
 
   def check_validity!
     keys = CHECKS & options.keys
-
-    if keys.empty?
-      raise ArgumentError, 'Patterns unspecified. Specify the :content_type option.'
-    end
+    raise ArgumentError, 'Patterns unspecified. Specify the :content_type option.' if keys.empty?
 
     keys.each do |key|
       value = options[key]
+      raise ArgumentError, ":#{key} must be a String or a Regexp or an Array" unless valid_content_type_option?(value)
 
-      unless valid_content_type_option?(value)
-        raise ArgumentError, ":#{key} must be a String or a Regexp or an Array"
-      end
+      next unless key.is_a?(Array) && key == :content_type
 
-      if key.is_a?(Array) && key == :content_type
-        options[key].each do |val|
-          raise ArgumentError, "#{val} must be a String or a Regexp" unless val.is_a?(String) || val.is_a?(Regexp)
-        end
+      options[key].each do |val|
+        raise ArgumentError, "#{val} must be a String or a Regexp" unless val.is_a?(String) || val.is_a?(Regexp)
       end
     end
   end
 
   def validate_each(record, attribute, value)
-    raise(ArgumentError, 'A CarrierWave::Uploader::Base object was expected') unless value.kind_of? CarrierWave::Uploader::Base
-    value = (options[:tokenizer] || DEFAULT_TOKENIZER).call(value) if value.kind_of?(String)
-    return if value.length == 0
+    raise(ArgumentError, 'A CarrierWave::Uploader::Base object was expected') unless value.is_a? CarrierWave::Uploader::Base
+
+    value = (options[:tokenizer] || DEFAULT_TOKENIZER).call(value) if value.is_a?(String)
+    return if value.length.zero?
 
     CHECKS.each do |key|
       next unless check_value = options[key]
+
       do_validation(value, check_value, key, record, attribute) if key == :content_type
     end
   end
@@ -57,16 +54,17 @@ class FileMimeTypeValidator < ActiveModel::EachValidator
   private
 
   def valid_content_type_option?(content_type)
-    return true if %w{Array String Regexp}.include?(content_type.class.to_s)
+    return true if %w[Array String Regexp].include?(content_type.class.to_s)
+
     false
   end
 
   def do_validation(value, pattern, key, record, attribute)
     if pattern.is_a?(String) || pattern.is_a?(Regexp)
-      return if value.file.content_type.send((pattern.is_a?(String) ? '==' : '=~' ), pattern)
+      return if value.file.content_type.send((pattern.is_a?(String) ? '==' : '=~'), pattern)
     else
       valid_list = pattern.map do |p|
-        value.file.content_type.send((p.is_a?(String) ? '==' : '=~' ), p)
+        value.file.content_type.send((p.is_a?(String) ? '==' : '=~'), p)
       end
       return if valid_list.include?(true)
     end
@@ -78,4 +76,4 @@ class FileMimeTypeValidator < ActiveModel::EachValidator
 
     record.errors.add(attribute, MESSAGES[key], errors_options)
   end
-end
\ No newline at end of file
+end
diff --git a/app/views/api/invoices/list.json.jbuilder b/app/views/api/invoices/list.json.jbuilder
index 76e11a5b1..97336dab1 100644
--- a/app/views/api/invoices/list.json.jbuilder
+++ b/app/views/api/invoices/list.json.jbuilder
@@ -6,7 +6,7 @@ json.array!(@invoices) do |invoice|
   json.maxInvoices max_invoices
   json.extract! invoice, :id, :created_at, :reference, :invoiced_type, :avoir_date
   json.user_id invoice.invoicing_profile.user_id
-  json.total (invoice.total / 100.00)
+  json.total invoice.total / 100.00
   json.url invoice_url(invoice, format: :json)
   json.name invoice.invoicing_profile.full_name
   json.has_avoir invoice.refunded?