diff --git a/fluentd.gemspec b/fluentd.gemspec
index 83c5abc18d..43e8ae07bb 100644
--- a/fluentd.gemspec
+++ b/fluentd.gemspec
@@ -34,12 +34,9 @@ Gem::Specification.new do |gem|
   fake_platform = ENV['GEM_BUILD_FAKE_PLATFORM'].to_s
   gem.platform = fake_platform unless fake_platform.empty?
   if /mswin|mingw/ =~ fake_platform || (/mswin|mingw/ =~ RUBY_PLATFORM && fake_platform.empty?)
-    gem.add_runtime_dependency("win32-api", [">= 1.10", "< 2.0.0"])
     gem.add_runtime_dependency("win32-service", ["~> 2.3.0"])
     gem.add_runtime_dependency("win32-ipc", ["~> 0.7.0"])
     gem.add_runtime_dependency("win32-event", ["~> 0.6.3"])
-    gem.add_runtime_dependency("windows-api", ["~> 0.4.5"])
-    gem.add_runtime_dependency("windows-pr", ["~> 1.2.6"])
     gem.add_runtime_dependency("certstore_c", ["~> 0.1.7"])
   end
 
diff --git a/lib/fluent/command/fluentd.rb b/lib/fluent/command/fluentd.rb
index 2150ece521..088af53b8b 100644
--- a/lib/fluent/command/fluentd.rb
+++ b/lib/fluent/command/fluentd.rb
@@ -189,9 +189,6 @@
 }
 
 if Fluent.windows?
-  require 'windows/library'
-  include Windows::Library
-
   opts.merge!(
     :winsvc_name => 'fluentdwinsvc',
     :winsvc_display_name => 'Fluentd Windows Service',
@@ -292,9 +289,7 @@
   case winsvcinstmode
   when 'i'
     binary_path = File.join(File.dirname(__FILE__), "..")
-    ruby_path = "\0" * 256
-    GetModuleFileName.call(0,ruby_path,256)
-    ruby_path = ruby_path.rstrip.gsub(/\\/, '/')
+    ruby_path = ServerEngine.ruby_bin_path
     start_type = Service::DEMAND_START
     if opts[:regwinsvcautostart]
       start_type = Service::AUTO_START
diff --git a/lib/fluent/plugin/file_wrapper.rb b/lib/fluent/plugin/file_wrapper.rb
index 0ef875b14e..91075a2aed 100644
--- a/lib/fluent/plugin/file_wrapper.rb
+++ b/lib/fluent/plugin/file_wrapper.rb
@@ -14,6 +14,8 @@
 #    limitations under the License.
 #
 
+require 'fluent/win32api'
+
 module Fluent
   module FileWrapper
     def self.open(path, mode='r')
@@ -36,19 +38,16 @@ def self.stat(path)
   end
 
   class WindowsFile
-    require 'windows/file'
-    require 'windows/handle'
-
     include File::Constants
-    include Windows::File
-    include Windows::Handle
 
     attr_reader :io
 
+    INVALID_HANDLE_VALUE = -1
+
     def initialize(path, mode='r')
       @path = path
       @io = File.open(path, mode2flags(mode))
-      @file_handle = _get_osfhandle(@io.to_i)
+      @file_handle = Win32API._get_osfhandle(@io.to_i)
       @io.instance_variable_set(:@file_index, self.ino)
       def @io.ino
         @file_index
@@ -68,7 +67,7 @@ def close
     def ino
       by_handle_file_information = '\0'*(4+8+8+8+4+4+4+4+4+4)   #72bytes
 
-      unless GetFileInformationByHandle.call(@file_handle, by_handle_file_information)
+      unless Win32API.GetFileInformationByHandle(@file_handle, by_handle_file_information)
         return 0
       end
 
@@ -122,7 +121,7 @@ def delete_pending
       bufsize = 1024
       buf = '\0' * bufsize
 
-      unless GetFileInformationByHandleEx.call(@file_handle, file_standard_info, buf, bufsize)
+      unless Win32API.GetFileInformationByHandleEx(@file_handle, file_standard_info, buf, bufsize)
         return false
       end
 
diff --git a/lib/fluent/supervisor.rb b/lib/fluent/supervisor.rb
index 854e53cb12..6f70ba885e 100644
--- a/lib/fluent/supervisor.rb
+++ b/lib/fluent/supervisor.rb
@@ -32,12 +32,6 @@
 require 'serverengine'
 
 if Fluent.windows?
-  require 'windows/library'
-  require 'windows/synchronize'
-  require 'windows/system_info'
-  include Windows::Library
-  include Windows::Synchronize
-  include Windows::SystemInfo
   require 'win32/ipc'
   require 'win32/event'
 end
@@ -235,7 +229,8 @@ def install_windows_event_handler
         end
         begin
           loop do
-            ipc_idx = ipc.wait_any(events.map {|e| e[:win32_event]}, Windows::Synchronize::INFINITE)
+            infinite = 0xFFFFFFFF
+            ipc_idx = ipc.wait_any(events.map {|e| e[:win32_event]}, infinite)
             event_idx = ipc_idx - 1
 
             if event_idx >= 0 && event_idx < events.length
diff --git a/lib/fluent/win32api.rb b/lib/fluent/win32api.rb
new file mode 100644
index 0000000000..d7757a8370
--- /dev/null
+++ b/lib/fluent/win32api.rb
@@ -0,0 +1,38 @@
+#
+# Fluentd
+#
+#    Licensed under the Apache License, Version 2.0 (the "License");
+#    you may not use this file except in compliance with the License.
+#    You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS,
+#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#    See the License for the specific language governing permissions and
+#    limitations under the License.
+#
+
+require 'fluent/env'
+
+module Fluent
+  module Win32API
+    require 'fiddle/import'
+    require 'fiddle/types'
+    extend Fiddle::Importer
+
+    if RUBY_PLATFORM.split('-')[-1] == "ucrt"
+      MSVCRT_DLL = 'ucrtbase.dll'
+    else
+      MSVCRT_DLL = 'msvcrt.dll'
+    end
+
+    dlload MSVCRT_DLL, "kernel32.dll"
+    include Fiddle::Win32Types
+
+    extern "intptr_t _get_osfhandle(int)"
+    extern "BOOL GetFileInformationByHandle(HANDLE, void *)"
+    extern "BOOL GetFileInformationByHandleEx(HANDLE, int, void *, DWORD)"
+  end if Fluent.windows?
+end
diff --git a/lib/fluent/winsvc.rb b/lib/fluent/winsvc.rb
index 8cfb807e43..d371922382 100644
--- a/lib/fluent/winsvc.rb
+++ b/lib/fluent/winsvc.rb
@@ -17,14 +17,10 @@
 begin
 
   require 'optparse'
-  require 'windows/debug'
-  require 'Windows/Library'
   require 'win32/daemon'
   require 'win32/event'
 
   include Win32
-  include Windows::Library
-  include Windows::Debug
 
   op = OptionParser.new
   opts = {service_name: nil}
@@ -37,16 +33,14 @@
   end 
 
   def read_fluentdopt(service_name)
-    require 'win32/Registry'
+    require 'win32/registry'
     Win32::Registry::HKEY_LOCAL_MACHINE.open("SYSTEM\\CurrentControlSet\\Services\\#{service_name}") do |reg|
       reg.read("fluentdopt")[1] rescue ""
     end
   end
 
   def service_main_start(service_name)
-    ruby_path = 0.chr * 260
-    GetModuleFileName.call(0, ruby_path,260)
-    ruby_path = ruby_path.rstrip.gsub(/\\/, '/')
+    ruby_path = ServerEngine.ruby_bin_path
     rubybin_dir = ruby_path[0, ruby_path.rindex("/")]
     opt = read_fluentdopt(service_name)
     Process.spawn("\"#{rubybin_dir}/ruby.exe\" \"#{rubybin_dir}/fluentd\" #{opt} -x #{service_name}")
diff --git a/test/plugin/test_file_wrapper.rb b/test/plugin/test_file_wrapper.rb
index 380cb4257c..93e7e61fbc 100644
--- a/test/plugin/test_file_wrapper.rb
+++ b/test/plugin/test_file_wrapper.rb
@@ -2,11 +2,6 @@
 require 'fluent/plugin/file_wrapper'
 
 class FileWrapperTest < Test::Unit::TestCase
-  require 'windows/file'
-  require 'windows/error'
-  include Windows::File
-  include Windows::Error
-
   TMP_DIR = File.dirname(__FILE__) + "/../tmp/file_wrapper#{ENV['TEST_ENV_NUMBER']}"
 
   def setup