diff --git a/ChangeLog b/ChangeLog
index 592c5c6ad9..f6f5183ee6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sat Jun 26 07:59:18 2010  Masaki Suketa <masaki.suketa@nifty.ne.jp>
+
+	* test/win32ole/test_win32ole_method.rb (test_offset_vtbl): check
+	  that OS is Windows 32bit or Windows 64bit in order to get
+	  correct offset value.
+
 Sat Jun 26 04:39:12 2010  Masaya Tarui  <tarui@ruby-lnag.org>
 
 	* ext/dl/lib/dl/func.rb (call): don't overwrite original arguments
diff --git a/test/win32ole/test_win32ole_method.rb b/test/win32ole/test_win32ole_method.rb
index 762ef1d795..2be93ab070 100644
--- a/test/win32ole/test_win32ole_method.rb
+++ b/test/win32ole/test_win32ole_method.rb
@@ -108,8 +108,29 @@ if defined?(WIN32OLE_METHOD)
       assert_equal(1610743810, @m_namespace.dispid)
     end
 
+    def is_win64?
+      if /win64$/ =~ RUBY_PLATFORM
+        return true
+      end
+      require 'Win32API'
+      get_current_process = Win32API.new('kernel32', 'GetCurrentProcess', nil, 'i')
+      handle = get_current_process.call
+      is_wow64 = false
+      begin
+        is_wow64_process = Win32API.new('Kernel32', 'IsWow64Process', ['i', 'p'], 'i')
+        bool = "\0\0\0\0"
+        if is_wow64_process.call(handle, bool) != 0
+          is_wow64 = bool != "\0\0\0\0"
+        end
+      rescue RuntimeError
+        # no IsWow64Process
+      end
+      is_wow64
+    end
+
     def test_offset_vtbl
-      assert_equal(24, @m_invoke.offset_vtbl)
+      exp = is_win64? ? 48 : 24
+      assert_equal(exp, @m_invoke.offset_vtbl)
     end
 
     def test_size_params