diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index e4f4e79b..1d169a87 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -42,7 +42,9 @@ Naming/AccessorMethodName:
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: snake_case, camelCase
 Naming/VariableName:
-  Enabled: false
+  Exclude:
+    - 'lib/**/*.rb'
+    - 'test/**/*.rb'
 
 # Offense count: 7
 # Configuration parameters: EnforcedStyle.
diff --git a/samples/gtk_ruby_zip.rb b/samples/gtk_ruby_zip.rb
index 4ce1cae0..a86f0a9e 100755
--- a/samples/gtk_ruby_zip.rb
+++ b/samples/gtk_ruby_zip.rb
@@ -18,14 +18,14 @@ def initialize
     add(box)
 
     @zipfile = nil
-    @buttonPanel = ButtonPanel.new
-    @buttonPanel.openButton.signal_connect(Gtk::Button::SIGNAL_CLICKED) do
+    @button_panel = ButtonPanel.new
+    @button_panel.open_button.signal_connect(Gtk::Button::SIGNAL_CLICKED) do
       show_file_selector
     end
-    @buttonPanel.extractButton.signal_connect(Gtk::Button::SIGNAL_CLICKED) do
+    @button_panel.extract_button.signal_connect(Gtk::Button::SIGNAL_CLICKED) do
       puts 'Not implemented!'
     end
-    box.pack_start(@buttonPanel, false, false, 0)
+    box.pack_start(@button_panel, false, false, 0)
 
     sw = Gtk::ScrolledWindow.new
     sw.set_policy(Gtk::POLICY_AUTOMATIC, Gtk::POLICY_AUTOMATIC)
@@ -42,27 +42,27 @@ def initialize
   end
 
   class ButtonPanel < Gtk::HButtonBox
-    attr_reader :openButton, :extractButton
+    attr_reader :open_button, :extract_button
     def initialize
       super
       set_layout(Gtk::BUTTONBOX_START)
       set_spacing(0)
-      @openButton = Gtk::Button.new('Open archive')
-      @extractButton = Gtk::Button.new('Extract entry')
-      pack_start(@openButton)
-      pack_start(@extractButton)
+      @open_button = Gtk::Button.new('Open archive')
+      @extract_button = Gtk::Button.new('Extract entry')
+      pack_start(@open_button)
+      pack_start(@extract_button)
     end
   end
 
   def show_file_selector
-    @fileSelector = Gtk::FileSelection.new('Open zip file')
-    @fileSelector.show
-    @fileSelector.ok_button.signal_connect(Gtk::Button::SIGNAL_CLICKED) do
-      open_zip(@fileSelector.filename)
-      @fileSelector.destroy
+    @file_selector = Gtk::FileSelection.new('Open zip file')
+    @file_selector.show
+    @file_selector.ok_button.signal_connect(Gtk::Button::SIGNAL_CLICKED) do
+      open_zip(@file_selector.filename)
+      @file_selector.destroy
     end
-    @fileSelector.cancel_button.signal_connect(Gtk::Button::SIGNAL_CLICKED) do
-      @fileSelector.destroy
+    @file_selector.cancel_button.signal_connect(Gtk::Button::SIGNAL_CLICKED) do
+      @file_selector.destroy
     end
   end
 
@@ -77,8 +77,8 @@ def open_zip(filename)
   end
 end
 
-mainApp = MainApp.new
+main_app = MainApp.new
 
-mainApp.show_all
+main_app.show_all
 
 Gtk.main