diff --git a/lib/rucaptcha/cache.rb b/lib/rucaptcha/cache.rb
index d82b23c..35bc482 100644
--- a/lib/rucaptcha/cache.rb
+++ b/lib/rucaptcha/cache.rb
@@ -33,9 +33,7 @@ module RuCaptcha
         return @cache if defined?(@cache)
 
         cache_path = Rails.root.join('tmp', 'cache', 'rucaptcha')
-        if !File.exists? cache_path
-          FileUtils.mkdir_p(cache_path)
-        end
+        FileUtils.mkdir_p(cache_path) unless File.exist? cache_path
         @cache = ActiveSupport::Cache::FileStore.new(cache_path)
         @cache.clear
         @cache
diff --git a/lib/rucaptcha/captcha.rb b/lib/rucaptcha/captcha.rb
index 2b2cca9..05beded 100644
--- a/lib/rucaptcha/captcha.rb
+++ b/lib/rucaptcha/captcha.rb
@@ -37,16 +37,13 @@ module RuCaptcha
         full_width   = font_size * chars.size
         size         = "#{full_width}x#{full_height}"
         half_width   = full_width / 2
-        full_height  = full_height
-        half_height  = full_height / 2
         text_top     = 0
         text_left    = 0 - (font_size * 0.28).to_i
-        stroke_width  = (font_size * 0.05).to_i + 1
+        stroke_width = (font_size * 0.05).to_i + 1
         text_width   = font_size + text_left
-        label = "=#{' ' * (chars.size - 1)}="
+        text_opts    = []
+        line_opts    = []
 
-        text_opts = []
-        line_opts = []
         chars.each_with_index do |char, i|
           rgb = random_color
           text_color = "rgba(#{rgb.join(',')}, 1)"
@@ -76,14 +73,14 @@ module RuCaptcha
           command = "convert -size #{size} xc:White -gravity Center -weight 12 -pointsize 20 -annotate 0 \"#{code}\" -trim #{png_file_path}"
           require 'open3'
           _stdout_str, stderr_str = Open3.capture3(command)
-          raise "RuCaptcha: #{stderr_str.strip}" if stderr_str != nil && stderr_str.length > 0
+          raise "RuCaptcha: #{stderr_str.strip}" if stderr_str.present?
           png_file_path
         else
           command.strip!
-          pid, stdin, stdout, stderr = POSIX::Spawn.popen4(command)
+          pid, _, stdout, stderr = POSIX::Spawn.popen4(command)
           Process.waitpid(pid)
           err = stderr.read
-          raise "RuCaptcha: #{err.strip}" if err != nil && err.length > 0
+          raise "RuCaptcha: #{err.strip}" if err.present?
           stdout.read
         end
       end
diff --git a/lib/rucaptcha/controller_helpers.rb b/lib/rucaptcha/controller_helpers.rb
index e143515..ceb9c76 100644
--- a/lib/rucaptcha/controller_helpers.rb
+++ b/lib/rucaptcha/controller_helpers.rb
@@ -7,7 +7,7 @@ module RuCaptcha
     end
 
     def generate_rucaptcha
-      session[:_rucaptcha]   = RuCaptcha::Captcha.random_chars
+      session[:_rucaptcha]    = RuCaptcha::Captcha.random_chars
       session[:_rucaptcha_at] = Time.now.to_i
 
       RuCaptcha::Captcha.create(session[:_rucaptcha])
diff --git a/lib/rucaptcha/view_helpers.rb b/lib/rucaptcha/view_helpers.rb
index f9fbec6..d491203 100644
--- a/lib/rucaptcha/view_helpers.rb
+++ b/lib/rucaptcha/view_helpers.rb
@@ -1,13 +1,13 @@
 module RuCaptcha
   module ViewHelpers
     def rucaptcha_input_tag(opts = {})
-      opts[:name] = '_rucaptcha'
-      opts[:type] = 'text'
-      opts[:autocorrect] = 'off'
+      opts[:name]           = '_rucaptcha'
+      opts[:type]           = 'text'
+      opts[:autocorrect]    = 'off'
       opts[:autocapitalize] = 'off'
-      opts[:pattern] = '[0-9a-z]*'
-      opts[:maxlength] = RuCaptcha.config.len
-      opts[:autocomplete] = 'off'
+      opts[:pattern]        = '[0-9a-z]*'
+      opts[:maxlength]      = RuCaptcha.config.len
+      opts[:autocomplete]   = 'off'
       tag(:input, opts)
     end