diff --git a/ChangeLog b/ChangeLog
index d65842e99c..7aaedb65a9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Nov 28 15:37:17 2012  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* configure.in: fix r37294: run only on i[3-6]86-linux.
+
 Wed Nov 28 15:31:11 2012  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* io.c (FMODE_SYNCWRITE): removed unused macro.
diff --git a/configure.in b/configure.in
index 295894feee..c916cd5834 100644
--- a/configure.in
+++ b/configure.in
@@ -1534,6 +1534,18 @@ AS_CASE(["$target_os"],
 [])
 
 
+AS_CASE(["$target_cpu-$target_os"], [[i[3-6]86-linux*]], [
+	 AC_CACHE_CHECK([for __sync_val_compare_and_swap], [rb_cv_gcc_compiler_cas], [
+			 AC_TRY_LINK([unsigned long atomic_var;],
+				     [
+				      __sync_val_compare_and_swap(&atomic_var, 0, 1);
+				      ],
+				      [rb_cv_gcc_compiler_cas=yes],
+				      [rb_cv_gcc_compiler_cas=no])])
+	 if test "$rb_cv_gcc_compiler_cas" = no; then
+		 ARCH_FLAG="-march=i486"
+	 fi])
+
 AC_CACHE_CHECK(for signbit, rb_cv_have_signbit,
   [AC_TRY_LINK([
 #include <math.h>