diff --git a/app/controllers/ru_captcha/captcha_controller.rb b/app/controllers/ru_captcha/captcha_controller.rb
index ef4d729..c85afbf 100644
--- a/app/controllers/ru_captcha/captcha_controller.rb
+++ b/app/controllers/ru_captcha/captcha_controller.rb
@@ -4,7 +4,11 @@ module RuCaptcha
       headers['Cache-Control'] = 'no-cache, no-store, max-age=0, must-revalidate'
       headers['Pragma'] = 'no-cache'
 
-      send_data generate_rucaptcha, disposition: 'inline', type: 'image/png'
+      if Gem.win_platform?
+        send_file generate_rucaptcha, disposition: 'inline', type: 'image/png'
+      else
+        send_data generate_rucaptcha, disposition: 'inline', type: 'image/png'
+      end
     end
   end
 end
diff --git a/lib/rucaptcha/captcha.rb b/lib/rucaptcha/captcha.rb
index b0644d3..34f8e3e 100644
--- a/lib/rucaptcha/captcha.rb
+++ b/lib/rucaptcha/captcha.rb
@@ -60,12 +60,21 @@ module RuCaptcha
           -implode #{RuCaptcha.config.implode} -trim label:- png:-
         CODE
 
-        command.strip!
-        pid, stdin, stdout, stderr = POSIX::Spawn.popen4(command)
-        Process.waitpid(pid)
-        err = stderr.read
-        raise "RuCaptcha: #{err.strip}" if err != nil && err.length > 0
-        stdout.read
+        if Gem.win_platform?
+          png_file_path = Rails.root.join('tmp', 'cache', "#{code}.png")
+          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
+          png_file_path
+        else
+          command.strip!
+          pid, stdin, stdout, stderr = POSIX::Spawn.popen4(command)
+          Process.waitpid(pid)
+          err = stderr.read
+          raise "RuCaptcha: #{err.strip}" if err != nil && err.length > 0
+          stdout.read
+        end
       end
     end
   end
diff --git a/spec/ocr_spec.rb b/spec/ocr_spec.rb
index efe9e38..30e9bc2 100644
--- a/spec/ocr_spec.rb
+++ b/spec/ocr_spec.rb
@@ -1,15 +1,17 @@
 require 'spec_helper'
 require 'fileutils'
+require 'tmpdir'
 
 describe 'OCR' do
   before do
+    @tmp_dir = Dir.mktmpdir
     @samples = []
     10.times do
       @samples << SecureRandom.hex(2)
     end
     @filenames = []
     @samples.each do |chars|
-      fname = File.join(File.dirname(__FILE__), "..", "tmp", "#{chars}.png")
+      fname = File.join(@tmp_dir, "#{chars}.png")
       img = RuCaptcha::Captcha.create(chars)
       File.open(fname, 'w+') do |f|
         f.puts img
@@ -19,14 +21,13 @@ describe 'OCR' do
   end
 
   after do
-    path = File.expand_path File.join(File.dirname(__FILE__), '..', 'tmp/*.png')
-    FileUtils.rm_f(path)
+    FileUtils.rm_f(@tmp_dir)
   end
 
   it 'should not read by OCR lib' do
     results = []
     @samples.each do |chars|
-      str = RTesseract.new(File.join(File.dirname(__FILE__), "..", "tmp", "#{chars}.png"), processor: 'mini_magick').to_s
+      str = RTesseract.new(File.join(@tmp_dir, "#{chars}.png"), processor: 'mini_magick').to_s
       results << "- Chars: #{chars}, OCR read #{str.strip}"
       expect(chars).not_to eq(str)
     end