diff --git a/ChangeLog b/ChangeLog
index 9bd49c261c..976f9ab947 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Sun Apr 22 17:44:37 2001  WATANABE Hirofumi  <eban@ruby-lang.org>
+
+	* configure.in: add -mieee to CFLAGS on Linux/Alpha
+	  to disable "DIVISION BY ZERO" exception.
+
+	* configure.in: remove -ansi on OSF/1.
+
 Wed Apr 18 04:37:51 2001  Wakou Aoyama  <wakou@fsinet.or.jp>
 
 	* lib/cgi.rb: CGI::Cookie: no use PATH_INFO.
diff --git a/configure.in b/configure.in
index 9171203105..9cd889871f 100644
--- a/configure.in
+++ b/configure.in
@@ -251,6 +251,11 @@ freebsd*)	LIBS="-lm $LIBS"
 			fi
 		fi
 		;;
+linux*)		LIBS="-lm $LIBS"
+		case "$target_cpu" in
+		alpha*)
+		    CFLAGS="-mieee $CFLAGS" ;;
+		esac ;;
 *) LIBS="-lm $LIBS";;
 esac
 AC_CHECK_LIB(crypt, crypt)
@@ -925,9 +930,7 @@ case "$target_os" in
     	CFLAGS="$CFLAGS -DOS2"
 	;;
     osf*)
-	if test "$without_gcc" = "no" ; then
-	  CFLAGS="$CFLAGS -ansi"
-	else
+	if test "$without_gcc" = "yes" ; then
 	  # compile something small: taint.c is fine for this.
 	  # the main point is the '-v' flag of 'cc'.
 	  case "`cc -v -I. -c main.c -o /tmp/main.o 2>&1`" in