diff --git a/ChangeLog b/ChangeLog
index 7fe28bd6d8..ab24b731ba 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Thu May  6 22:19:38 2010  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* cont.c: define FIBER_USE_NATIVE only when _WIN32_WINNT >= 0x0400
+	  on Windows because Fiber APIs are supported only such building
+	  (and running) environments.
+	  [ruby-dev:41192]
+
 Thu May  6 19:13:43 2010  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
 
 	* test/openssl/test_ec.rb: added test_dsa_sign_asn1_FIPS186_3. dgst is
diff --git a/cont.c b/cont.c
index 57b960a99e..c164a3554b 100644
--- a/cont.c
+++ b/cont.c
@@ -14,7 +14,7 @@
 #include "gc.h"
 #include "eval_intern.h"
 
-#if (defined(_WIN32) || defined(HAVE_SETCONTEXT)) && !defined(__NetBSD__) && !defined(FIBER_USE_NATIVE)
+#if ((defined(_WIN32) && _WIN32_WINNT >= 0x0400) || defined(HAVE_SETCONTEXT)) && !defined(__NetBSD__) && !defined(FIBER_USE_NATIVE)
 #define FIBER_USE_NATIVE 1
 
 /* FIBER_USE_NATIVE enables Fiber performance improvement using system