diff --git a/ChangeLog b/ChangeLog
index 4f8d967ef7..af48f053d3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Jan 21 18:15:09 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in: should not use -Werror=* flags while conftests.
+
 Fri Jan 21 09:17:00 2011  Luis Lavena  <luislavena@gmail.com>
 
 	* configure.in: Fix incorrectly detected x86_64-w64-mingw32 due
diff --git a/configure.in b/configure.in
index ab3436ddd1..795d7f1bcf 100644
--- a/configure.in
+++ b/configure.in
@@ -469,6 +469,8 @@ if test "$GCC:${warnflags+set}:no" = yes::no; then
     AS_CASE([" $warnflags "],[*" -Wno-missing-field-initializers "*], [wflag=-Wextra],
                              [wflag=-Wall])
     RUBY_TRY_CFLAGS($wflag, [warnflags="$wflag${warnflags+ $warnflags}"])
+    rb_cv_warnflags="$warnflags"
+    warnflags=
 fi
 if test "$GCC" = yes; then
     RUBY_TRY_CFLAGS(-fvisibility=hidden, [RUBY_APPEND_OPTION(XCFLAGS, -fvisibility=hidden)])
@@ -2579,6 +2581,7 @@ if test "${ARCH_FLAG}"; then
     CXXFLAGS=`echo "$CXXFLAGS" | sed "s|$archflagpat"'|$(ARCH_FLAG)|'`
     LDFLAGS=`echo "$LDFLAGS" | sed "s|$archflagpat"'|$(ARCH_FLAG)|'`
 fi
+warnflags="$rb_cv_warnflags"
 AC_SUBST(cppflags, [])dnl
 AC_SUBST(cflags, ["$orig_cflags "'${optflags} ${debugflags} ${warnflags}'])dnl
 AC_SUBST(cxxflags, ["$orig_cxxflags "'${optflags} ${debugflags} ${warnflags}'])dnl